Thanks for the response. The skin belonging to a rat snake was my guess as well but since the first sighting of the one in the pic I've seen 2-3 smaller kings that have apparently taken up residence under my sidewalk. I found the large skin 3 feet from the opening where they are going in and 2 smaller skins within 20 ft. Do you know if the rat snakes and king snakes would stay in such close proximity to each other?