Sibley Labyrinth
This labyrinth is located in the Sibley Volcanic Regional Preserve run by the East Bay Regional Parks. The park service doesn't have any information on the labyrinth, probably because it is a man made thing.
Here are some nice pictures of a hike through the park that include two of the labyrinths. The main one is a classic 7-curcuit Cretan. This is the first Labyrinth I found and walked. I don't think the small one next to the main one is any specific type. I think it is one that wanders where there is room.
I was going to make a page all about this labyrinth because I couldn't find much information on it beforehand but I found this page. I think it is great and covers it all nicely except for a map. Guess what is on my page. It looks like I found the large labyrinth and a small one next to it. There is at least one more if not more elsewhere in the park. When I find them, or someone shows them to me, I will add them to the map.
Map