In 1977, Willie Nelson recorded To Lefty From Willie for his friend Lefty Frizzell. In 2009, Phosphorescent's Matthew Houck, who learned music listening to Nelson's slow-motion drawl, recorded To Willie (Dead Oceans) for a man he'd never met. Houck has since played Nelson's 76th birthday and performed with him at October's Farm Aid. David Gray (pictured), the English Dave Matthews, headlines. Tickets $49.30-$59.55 (including fees).