Thanks for the suggestions. The spanish mission makes sense, there's a few spanish missions nearby. The marking on the pottery remind me of markings I've seen on some pieces of Anasazi pottery I collected a while back. But, the Anasazi ones were 2 or 3x's as thick. I forgot to give a reference for size, these are very thin, maybe only 1/8" thick. Also, the Anasazi had a flat finish, these have a bit of a shine to them,possibly glazed. I think the pottery came from elsewhere, as there isn't a local source of clay in the surrounding area and the Tongva people were known for there bowls and similiar objects ground/carved from basalt, as well as weaved baskets, that were so tightly made,they could hold water. My understanding is that due to the clay situation, they didn't produce any pottery. Sorry, I didn't mean to withhold information.