It’s Monday night at the Texas Union. A trio of girls tote lattes and backpacks out of Starbucks; not far away, a few dozen students study textbooks in a new lounge, their bodies sprawled bulkily over sofas and chairs. The sound of music drifts in from the nearby Cactus Cafe. Will Wallace removes his guitar from around his neck, steps out from under the bright lights of the stage and takes his seat next to Larry Kerbo, a 59-year-old veteran of Austin’s music scene. It’s open mic night at the Cactus, and this Monday night crowd is extraordinary.