The few I have were found in Nevada. In Winnemucca and Carlin...both times mixed in with other chips I bought. The person in Carlin..an old Club owner told me they were from the Owl in Battle Mountain. I took one to Howdy..We found the "Card" from Mason showing that they were delivered to an address in S.F. in the 50's.
I think the Chip Rack and the Offical Chip Guide show the chip as coming from Battle Mountain. Cheers, Steve