It's been almost 35 years since Gram Parsons left his beautiful corpse in Joshua Tree, but the singer's following continues to grow. And for good reason: Parsons' cosmic country with the Byrds and the Flying Burrito Brothers presaged the alt-country sound by a couple of decades. Fans worship his honeyed croon and lonesome songs — though his good looks surely didn't hurt his legacy. Former Parchman Farm singer Eric Shea spearheads the Sleepless Nights tribute to the ghost of Gram; the eighth annual installment features an array of disciples, from straightforward tribute acts like the Sin City All-Stars to latter-day harmonizers such as excellent local quartet Mountain Bride.