... one day this Indian named Glode was out in his canoe. He had his little girl with him and when they got to a place where there is a point of land, he saw a ship sailing towards them. They were scared of strangers in those days, so he paddled to a cove and hid his canoe away in the woods. Then he climbed a tree. From there he could see everything that went on, and he watched that ship. It stopped, and the pirates on board took down the sails, lowered a rowboat, and four or five of them came ashore. They came straight to that point, chose a spot, and started digging. The captain gave the orders. After they got a trench dug deep enough, he sent two of them men to the boat for a big chest. After they had brought it up and put it down beside the hole he lined them all up and said, 'Have you got everything ready? Who's going to keep this money?' One of them says, 'Well, the other fellers don't say much. I'll look after it.'
'All right,' says the captain. 'You're to guard it for a hundred and fifty years,' and before the man realized what he had gotten himself into, the others grabbed him. They cut off his head then and put him in the hole with the chest. After that they drew a map, covered up the hole, and went away.
From Bluenose Ghosts, by Helen Creighton.
Last time I talked about Captain Kidd, and touched briefly on the subject of buried treasure. Kidd is the only pirate known to have buried treasure, on Gardiner's Island, only to have it stolen out from under him by his so-called friend the Earl of Bellomont. Which neatly illustrates the central problem with buried treasure: once buried, any idiot can dig it up and claim it for his own. In the movies, this might inspire a pirate to design some really over-elaborate traps, but as can be seen from the Creighton extract, a real pirate hasn't got the time or patience for Oak Island-style miraculous engineering. Just put your basic corpse in your basic hole, and you're good to go.
Now, it's unlikely that many, if any, pirates actually did kill a victim and bury him, or her, with the loot, if only because it's unlikely that many pirates buried loot. Loot is for spending, not sticking in the ground. That said, it's probable that someone tried that trick. Superstition has followed in humanity's footsteps since we learned how to walk, and no matter how bad an idea might be, you can always find someone who thinks it's a genius scheme. Besides, in an RPG world, the rules are as you make them. Why shouldn't a pirate kill a sacrificial victim to create a guardian for his treasure?
The great thing about a story like this is that you can play it out almost anywhere along the East Coast of the United States as well as on any of the islands in the Caribbean. With a bit of tweaking you could probably also put it somewhere along the English or French coast, changing the pirates to smugglers. Or somewhere off the coast of Africa, or anywhere along the old Pirate Round. Or ... but you take the point. That said, in Trail of Cthulhu and Cthulhu games in general, one of the favorite settings is Lovecraftian New England, with its legend-haunted small towns like Dunwich and Arkham, quiet and forbidding. A pirate tale of buried gold and ghostly guardians is a natural fit, and could be an interesting beginning to a campaign, as well as a brilliant reason for the characters to get together in the first place. A group of treasure hunters who get too close to Innsmouth for comfort? Sold!
But what do you get when you cut off someone's head and bury them with the loot? Legend is cagy on the subject. The ghost is supposed to haunt the spot, with or without a head. It has significant power to defend its loot, but can only use that power against someone trying to steal it. Someone just walking by, without the slightest idea that Thomas Tew, or whoever it might have been, left a fortune there, won't be disturbed. Well, probably not, anyway; Creighton reports that several ghosts, tired of standing watch, started pestering passers-by to take the loot from them, and let them rest.
The tale is very similar to the barrow-dweller or hagbui of Norse folklore, and the story probably found its way to Canada via Scotland, which has an old history of conflict with Viking raiders. These creatures are often created from the corpse of a warrior, and left behind to guard loot. A draugr has incredible strength, but it can also move through solid rock, in mist form, and increase its size to that of a giant. Its stench is awful, far beyond the usual pungent decomposition stink, and its presence can sometimes be detected by the foxfire that glows at its burial place at night. Iron is potent against them; to prevent the dead returning, people sometimes pierced the corpses' feet with iron nails.
Buried treasure can't just be unearthed. There's rules to this sort of thing. Even if the ghost wants you to dig up the loot, it's bound by geas to defend it, so you might get attacked. Each treasure can be uncovered without risk so long as its ritual is carried out, and that ritual can vary from spilling the blood of a newborn, spilling the blood of twins, getting a hen and rooster to plough and seed the ground - no, really - and so on, and on. Each method is detailed by the pirates as they bury the loot, so if you want to know how to do it, better find a ouija board; or maybe someone helpfully wrote the ritual down somewhere. It's likely that a user of Goetic magic can think of ways past this barrier, or perhaps someone who knows the Saaamaaa Ritual can defuse the ghost's defenses.
When digging for treasure, you must go at night, and you must never, ever speak. Speaking gives the ghost power over you; until you speak, its abilities are limited, but once you speak, it can do as it pleases. Because of this, ghosts will usually try to trick you into speaking, using powers of illusion or suggestion to get you to say something. If you absolutely have to address a ghost, always invoke the power of God, as in 'In God's name, speak.' So long as you do that, its power is reduced.
If the ghost attains its full power, it can do a great deal. It has supernatural strength, and is capable of lifting or throwing great weights, far beyond the capacity of a normal human. It can summon other supernatural entities to help it. It can remove the treasure instantly, to another location, or deep underground where it can't be reached by digging. It will not hesitate to kill, but will not pursue a victim, so if the treasure hunters run away they won't suffer its further wrath. It's often armed, perhaps with sword, pistol or musket. Being a ghost, it probably can't be killed, and certainly not with conventional weapons.
Of course, that all assumes that a ghost really is a ghost, and follows Occult rules. It could as easily be the Devil, or one of the many Black Dogs. In a Mythos tale, it could also be something from beyond the stars, or a vampirish mist, or a Deep One compelled to return to the spot each night by a magic-using pirate, or ... again, you get the point. Such creatures don't need to follow the usual ghostly rules.
With all that in mind, here's a treasure for you:
Rooster Island's Gold
You've dreamed three nights running, a sure sign that the dream is a true one, that there's treasure buried out on Rooster Island, one of the tiny, rocky outcrops between Plum Island and the mainland, perhaps an hour by boat from Innsmouth. According to the dream, there's a large, flat rock, the size of a dinner table, not far from an immense elm tree. Under that rock is the treasure, but in your dream you've seen a coal-black kitten playing on that rock, and you believe that kitten has some significance, though you aren't sure precisely what. You're convinced a fortune lies out there for the taking, but aren't sure of the specifics.
Library Use, Oral History or similar discovers that Rooster Island was thought to be where Billy 'Black Dog' Seavy hid the loot from his piratical adventures during and after the war of 1812. Seavy, a Massachusetts-born filibuster, captured twelve ships in all, before being run aground and shot off the coast of Cuba, in 1816. His most notorious exploit is the capture of the merchantman Belle, when he's supposed to have locked the crew and passengers below decks and set the ship on fire. Seavy's mentioned in several books on witchcraft, as a pirate captain who supposedly could command the wind and waves, drawing victims in by stealing the wind from their sails and putting it in his own, or using storms to drive them towards him. Seavy's supposed to have boasted, before being filled full of grapeshot in the summer of 1816, that only the Devil knew where his loot was hid, and the Devil was obliged to keep it for a hundred years, or until an angel came knocking on the Devil's door.
Occult, in combination with information gained from the dream, can work out that the best time to get the treasure is an hour after midnight, when certain constellations are overhead, since that's the time the dreamer thinks the dream takes place. The kitten, probably a kind of guardian, needs to be pacified in some way, before the dig can take place.
Cthulhu Mythos knows that the stones on Rooster Island have strange, malign symbols carved on them, that cultists sometimes use in their dreadful rituals of appeasement and summoning. Lights have been seen on Rooster Island at night, and it's thought that necromancers come to that spot to summon up dreadful creatures, as messengers to their dark gods. Some Innsmouth families regularly make pilgrimage to Rooster Island and other places like it, dotted up and down the coast, always returning to the same spot year after year, as if called there.