Mike--you were 100% correct--now that I have the piece in front of me. It has a raised flamingo shape with the wording in the famous script below it: "Fabulous Flamingo" and in cap print: LAS VEGAS, NEVADA
On the reverse, is the CAP PRINT statement "DROP IN ANY
MAIL BOX RETURN POSTAGE GUARANTEED"
I'll get scanned a bit later, but that is the item.