You may wish to contact the Grace Balloch Memorial Library in Spearfish and ask for the Reference Desk. (605) 642-1330 to shed more light on what the initials stand for.
if they don't know, you can ask for the name and number of the county historian.
Good luck,
Don....
The attribution on tokencatalog of this maverick is based on one listed in Miedema's SD Tokens book which reads A.E.F. CLUB / BILLIARDS / SPEARFISH, S. DAKOTA - There are both 5¢ and 10¢ denominations of it listed there. Then, from the Queen City Mail newspaper of Spearfish, SD 29 Sep 1920 is this ad.
John in the Great 208