I have done a lot of research on this photograph but found very little. I believe he was at one time a pony express rider and later became a wild west show entertainer. I do not know for whom. He wears some short of shooting metal? All of his personal items are here for him and his horse., including his holstered Colt. You can see fringed chaps and some sort of pack on the floor. You can see a belt that reads (in part) "the Kid of". His name, A.L. Thompson is printed on the back of the mount and "The Lost Kid of the Plains". I'd love to know more!