http://cashcoinconnection.com/gamingchipsCalifornia/H/HaroldsClub/HaroldClub.html

John Kallman has an image of the El Centro $25 version that has the same style "Harold's Club" hotstamp. With an apostrophy BTW. Don's gotta be right about the Reno bidders. I've always heard there was great debate in Reno over various stores using $20 chips back in the day but I'd think you'll be looking for a long time to get some Reno $50's.