cap

Im not sure what this could be haha, any ideas? Aboute an inch tall and an inch and a half wide

Found in a field. Appears to be some sort of gasket material on back. Looks like a fuel cap to me but I'm not sure of the specifics. The center piece turns about 1/8 turn counter clockwise, then back again to it's original position. Seems to be designed that way rather than damaged.