I'm not sure where the chips are from?? I am leaning toward Northern California/Northern Nevada for my search for now because of the location of where they were found.
There are many Places with Rainbow in the name. Rainbow Tavern, Rainbow Inn and Rainbow Club.
I would think the chips are from the 40's to 50's....so my initial search with go with Clubs listed during those years. It's really a shot in the dark. I did find some of the other chips together with these. There were more than 1 of every chip found. So...maybe a clue with the KEN or RC chips. The guy I got them from said they came from his sister and were passed down from her husbands side of the family. I have no name to go off of...but if I run into a guy named Ken who owned a Rainbow Club....might be onto something.
With a quick search I found a Rainbow Club in .....
Marysville, Ca 1960's
Roseville,Ca 1960's-70's
Reno, Nv 1930's-40's ( I think there are 2 different places with same name)....
Unless someone already knows.....we might never know...only speculate 🤔