Garth Brooks and Trisha Yearwood were two of the surprise guests at the Country Music Hall of Fame's Ford Theater on Tuesday night (Sept. 30). Brooks and Yearwood performed at the request of Dobro player Jerry Douglas, who has served as the Hall of Fame's artist-in-residence this year. John Cowan, Tim O'Brien and Maura O'Connell also sang at the concert, which was the fourth and final installment of Douglas' artist-in-residence series.