The San Antonio Blues Society returns with its annual showcase celebrating the genre. At 16 and 18 years old, Alex and Glenn Peterson are two of the brightest young stars in the Austin blues scene. With verbose bass and classic blues guitar, the duo is in the process of recording their debut effort. With Rob Roy Parnell. $15-$50, noon, Sam’s Burger Joint, 330 E. Grayson, (210) 223-2830