With the long days of summer comes the sweaty undershirt of nostalgia, and the mind tumbles back to the summer vacations of yore. The young brain reeled at the possibilities of an infinite summer stretching out just on the other side of 3 p.m., on the last day of school. Now we watch the clock for 5. But with summer concert series upon us, it's almost like those summer vacations: having things to do outside so you don't have to go home. Lewis Ginter's Groovin' in the Garden series always seems to air-dry that undershirt with big-kid diversions, such as superb bluegrass trio The Avett Brothers, which kicks off the series with opener the Seldom Scene, Thursday, May 10, at 6 p.m. The Avett Brothers push the boundaries of Americana, asking what isn't included in the genre. And they get to act like big kids, too, up there onstage. Tickets are $15-$20. Call 262-9887 or www.richmondconcerts.net.