I found this last year in the back yard of a 70+ year old house. It was about 7 inches deep and the signal almost blew my ears out. I figured it was a screw cap and almost passed it by!
Looks like someone else found one in streeter's club, here's a quote:
"Surprisingly enough the first item I found was a Captain Midnight Brass Spinner Membership Token. It has "Captain Midnight 1940 Flight Patrol Metal of Membership" on one side and figures and names of the program?s three principal characters on the other. It also has the Skelly Oil Company Logo with no "r" below indicating it is an original rather than a reproduction. It?s value would be over $20 if mint."
Pretty sure it's brass Jeff. It doesn't have the "r" denoting a reproduction, so it's an original. Unfortunately it's not in mint condition but still in pretty good shape nevertheless.