I’ve been having trouble getting material on Scilly: enough to go forward, but I’ve written to various people for help finding folklore. Let’s begin.
The capital of Scilly in the 20th Century is St Mary’s, but in the C13th, it’s what’s now called “Old Town”. In period I think it’s called Ennor (although that could just be “Old Town in Cornish.) My notes also say it was called St Mary’s, and after and inundation they moved the town.
There are a series of charters giving all of Scilly to the abbots of Tavistock. Later, they may belong to Tresco? That being said the king seems to send governors to the island, who are also constables of the castle at Ennor, and they seem to have rights over the islands as well. The yearly fee for the islands, in the C13th, was six shillings and eight pence, or 300 puffins. There is no record of this payment ever actually being made in seabirds. The governor also had to pay for twelve men at arms to keep the peace on the island.
There are two giant sites in the Scilly Isles: Giant’s Castle and Giant’s Punchbowl. The punchbowl is a Logan stone.
In the 17th century ore-weed (kelp) was harvested and burned in kilns, to make alkali for glass and soap. This might work for a covenant.
There is a white narcissus (called a “Scilly White”) which might work as a vis source. A relative is found near St Michael Mount. I need to alos check out other famous flowers grown here in the C19th. (Soleil d’Ors, Grand Monarques, Pheasant Eyes, and the Yellow Daffodil).
Some people claim that Lyonesse refers to the roar of the water between Cornwall and the Scilly Isles. That’s a water elemental/faerie.
Games From Folktales 