The CML (handwritten on bottom of card as CMC)...but it does look like L to me too.
I tried to figure out where they were used, but my access to Oakland Directories stops at 1957. These were sent in 1976.

Louis Stayer
487 Merrit Ave
Oakland, Ca 1976

900 total chips.
White , yellow , red, black
I have 2 Red and 1 white chip (that I can find)

***Oakland is one of the library’s I plan on visiting in the next 2-3 months. Oakland is one of California’s major cities and there hasn’t been a lot of research done there. I would think there was 30-50 Card rooms in Oakland’s past. Most likely more.