A pal of mine was doing some packing the other day and came across these plates. He decided to Google the maker of them and found out they were made in Manhattan Beach, so he sent me a couple pics. Metlox was a ceramics manufacturer near downtown Manhattan Beach from 1927 to 1988. Today its the site of a sort of strange shopping center that kept the same name in homage to the old factory. I had never seen anything Metlox made, and was surprised to see that these were such a modernist design; he said he found out these were part of a Metlox line called "California Freeform." Kinda crazy the way things connect sometimes.
[apologies for blog posts before 1/2009 that are not yet updated to format]