After bumbling through Cal Flora, Wikipedia, and some other resources, I have a list of candidates to check into. My girlfriend's dad had suggestions on native fern types, and I ended up finding a very likely candidate, the California Maidens Hair Fern. However, I'll have to buy one somewhere, since collecting a cutting from the wild runs the risk of spreading the fungus-like organism that causes Sudden Oak Death. Nothing is ever easy!
I also realized I didn't know what kind of soil and beneficial organisms(like isopods and springtails) would be used in a temperate vivarium. Originally I planned on ABG Mix or reptisoil(or a similar alternative) mixed with other stuff, but hadn't considered that ABG is intended for tropical vivariums. Now I'm not quite sure what to use.