This hardscrabble Mississippi-based blues label continues its series of recordings from musicologist George Mitchell’s ‘60s archives with the first taped performances of R.L. Burnside, one of its keystone artists. Although it might seem that Burnside’s career has been hyper-documented, there are some real surprises here. The opening "Like a Bird Without a Feather," unavailable elsewhere, is the first: it’s a sad lament about a lost love set to the kind of rolling guitar figure that John Lee Hooker patented, and only after the narrator’s tear-streaked voice has your sympathy does he admit that he shot her down in cold blood.

Burnside staples like "Goin’ Down South," "Jumper on the Line," "Poor Black Mattie," and "Long Haired Doney" are here in bare-boned acoustic versions. And this early take on "Skinny Woman" — covered recently by the North Mississippi All Stars — melds the rippling style of picking associated with John Hurt to percussive passages of Burnside beating his knuckles against his six-string’s body. That’s a feat he’s yet to repeat on record. The small savory helping of slide guitar is best heard on Robert Johnson’s "Walkin’ Blues," with Burnside uncharacteristically favoring the low strings for his steel-on-steel grinding — save for the solo break, which stabs into the high register with measured authority. And the youthful flexibility in Burnside’s voice here allows him to soak all sorts of emotional nuances from these 14 songs. If you’ve never heard country blues played at its richest by a modern master, this is an ideal place to start.