I played in the 30s in California, and we used milk bottle caps. (Some of them were considered quite rare like buttermilk caps from different dairies.) We were between six and twelve, and played on any hard surface, in a circle. When your milk bottle cap landed on top of somebody else’s cap, theirs was eliminated from the board and you got to keep it. If all your caps were eliminated, you were out.
Original author: Bob Peterson [e-mail]