“When the Stars Begin to Fall: Imagination and the American South” is an appealing mash-up of fine art and folk art either made in the South or inspired by its mythology. Well-known insider artists, such as Kara Walker, Theaster Gates and David Hammons, are featured. But the show’s energy stems from the surprising juxtapositions and correspondences of insiders and outsiders. Large recent paintings of nude black figures by Kerry James Marshall, for instance, play counterpoint to two imposing figurative assemblages by Besse Harvey, which recall ritual cult objects. Elsewhere, homespun textile pieces by Marie “Big Mama” Roseman echo the embroidered look of Frank Albert Jones’s intricate colored-pencil drawings.