I liked the suggestion of incorporating a playing card. I thought maybe this guy would be superstitious so he believes in the power of lucky charms (not the cereal) He spends his day digging tunnels, searching for that elusive treasure, and a few mementos have stuck with him, and in some instances have "saved his life" One such item was a joker card from a very old deck, as well as an old bear claw. Each time he excavated one of these items, he went to the surface to get a better look at them, and each time he surfaced, the tunnel collapsed not moments afterward. From that point on, he's carried them with him wherever he goes.