I recently found four metal (aluminum?) discs in an old file card cabinet I bought from Kentucky surplus. Three are 2" in diameter, have a letter "L" stamped on top, "KENTUCKY" stamped under that, a larger 2 to 4 digit number and "REGISTERED MOTOR VEHICLE" around the bottom half. Three have a hole in the center for screwing on and one has a slot at the top,like for hanging and has the two digit number and a "B" instead of "L". Anyone ever seen anything like these at a rally? I remember back to late 40's and only remember rectangular tags. Any value?