It's not hyperbole that leads us to call this astonishing collection of trolley signs from the 1920s and 1930s a buried treasure. The signs, emblazoned with slogans for everything from Lucky Strike cigarettes to Campbell's Soup to Super Suds to Iodine Tooth Whitener to Sun-Maid Raisins, were actually discovered buried inside a wall after apparently being used as insulation. They obviously have seen better days, and some are quite fragile, yet their vivid colors and All-American themes -- "Don't those folks look happy around their own fireplace?" reads the sign for Blair Home Company -- revive the optimism and promise of those innocent times.