The Hound

This particularly chilling short story was inspired by a trip that Lovecraft made with Rheinhart Kleiner to the 18th-century Dutch Reformed Church on Flatbush Avenue in Brooklyn - and to its adjascent graveyard, full of grave markers dating from the mid-1700s. While there, Lovecraft pocketed a piece of one of the grave markers; and it set him to thinking about the possibilities of a story plot in which a vengeful tomb-denizen, resenting a similar act of souvenir-taking, claws its way out of the grave to track down the desecrator.
That story idea led him directly to "The Hound."