Watch Warren Haynes, Billy Gibbons Sing ‘Workin’ Man Blues’ at Haggard TributeWatch Warren Haynes, Billy Gibbons Sing ‘Workin’ Man Blues’ at Haggard TributeWarren Haynes and Billy Gibbons covered Merle Haggard's "Workin' Man Blues" at the 'Sing Me Back Home: The Music of Merle Haggard' tribute concert.Carrie HortonCarrie Horton