Garrison Keillor Tonight is an evening of stand-up, storytelling, audience song, and poetry. One man, one microphone. There are sung sonnets, limericks and musical jokes, and the thread that runs through it is the beauty of growing old. There is the News from Lake Wobegon, a town booming with new entrepreneurs, makers of artisanal firewood and gourmet meatloaf, breeders of composting worms, and dogs trained to do childcare. But some things endure, such as the formation of the Living Flag on Main Street, citizens in tight formation wearing red, white or blue caps, and Mr. Keillor among them, standing close to old neighbors, Myrtle Krebsbach (“Truckstop”) and Julie Christensen (“Bruno, The Fishing Dog”) and Clint Bunsen. And an a cappella sing-along with the audience singing from memory an odd medley of patriotic songs, pop standards, hymns, and ending with the national anthem. Garrison Keillor brings his inimitable stories of the places we all know in our heart to the stage tonight.