Showing the impact of Swamp Blues on other music , the Rolling Stones played a version of Slim Harpo 's `` I 'm a King Bee , '' and Neil Young recorded Slim Harpo 's `` Rainin ' In My Heart . '' Attesting to the impact of swamp blues on popular music , the Rolling Stones covered swamp bluesman Slim Harpo 's `` I 'm a King Bee '' , while Neil Young , among others , recorded Harpo 's `` Rainin ' In My Heart . ''