Their name is a tip of the hat to the pioneering black string band The Tennessee Chocolate Drops, and these three history lovers are classic folkies — students of old-time techniques and subject matter. The Carolina Chocolate Drops delve into the tangled history of 20th century African-American music, with nods to vaudeville, blues and the jug-band tradition exemplified by Gus Cannon. The band played The Grand Ole Opry in 2008, and a group such as the Chocolate Drops is now the norm, not the exception — these days, everybody seems hip to such once-forgotten figures as Cannon and Noble Sissle. These groups remind listeners how pop music and "folk" music interacted in the 20th century to produce modern rhythm-and-blues. On last year's full-length Genuine Negro Jig, producer Joe Henry nudged them toward the present with a cover of Blu Cantrell's 2001 single "Hit 'Em Up Style (Oops!)."