Now free on Archive.org, a huge encyclopaedic compendium of folk-beliefs about the ‘active supernatural’, that could still be found being expressed by folks in America during the 1930s. The beliefs are exhaustively categorised by type, in the manner of the theme-sorting ethnographic folklorists and fairy-tale sifters of the period (sadly, sci-fi has never had a similarly completist look-up volume containing an index of all of its themes and concepts).
Many of the book’s ‘folklore collecting points’ overlap with areas encompassed by Lovecraft’s annual summer travels.
My red dots, for clarity. South Carolina is a probable dot as well, but I can’t be sure.
This defunct historical lore is possibly most useful, these days, as a set of Oblique Strategies-like ideas which writers can use to inspire new works. Open at random three times, pick an idea randomly from each of the three pages, then think of a setting that might contain and combine them all in some way. Add characters, and devise the skeleton plot framework.