Willie Nelson and Merle Haggard's biggest hit came from an impromptu recording session at 5 a.m., post-10-day-cayenne juice cleanse.

Shooter Jennings and the Werewolves of Los Angeles will bring a genre-blending set that mixes Jennings' own catalog with the songs of Warren Zevon, while Ben Haggard, son of country legend Merle ...