The New York Times ran an article yesterday about the upcoming digitization (and availability) of Alan Lomax's collection of field recordings, notes, films and pictures made over his long career. Truly global in scope, his archive covers much of world folk music.
I just learned of Bessie Jones and the Georgia Sea Island Singers.
"Ms. Jones was an influential singer on St. Simons Island, Ga., where this selection was recorded on Oct. 12, 1959. She and Lomax collaborated to make her group, the Georgia Sea Island Singers, a national touring act that performed at the Newport Folk Festival and President Jimmy Carter's inauguration." - from the multimedia page that accompanied the above article.