My group recently came across Thaumaturgical Prodigies in the New-England Canaan. They decided to skim it, which prompted me to hint at the strange history of Billington's Wood northwest of Arkham (inspired by the Keeper's Compendium.) They might be inclined to visit it shortly!
What other sources besides Arkham Unveiled and the Keeper's Compendium provide background on the place? I am particularly interested in original literary sources. Is the story "Strange Manuscript Found in the Vermont Woods" the place where it was first mentioned?