Notes:
Ok not completely sure about the id on this one, but it seems to be the closest I can get to. This is russula, with very yellow gills, an off-white/yellow cap color, and mild taste.

The mild taste and yellow gills put into one class of Russula, by Thiers’ Russula section of the Agaricales of CA. Having a off-white/yellow cap seems to id it as either: R. flaviceps, R. albida, and R. basifurcata. R. basifurcata is only in the mountains right after the spring snow melt, so its not that one. R. flaviceps is supposed to be bright “intense” lemon-yellow, pretty much all over. This one is yellow, but I wouldn’t say it is “intense” lemon-yellow. So, that leaves me R. albida.

Which it seems to match the discription fairly well, except: the stipe is too short (no biggy), it is listed as being found in the coastal areas of Marin and Mendocino Counties (which I guess is close enough really), and the stipe in the discription is hollow to stuffed — this stipe was solid, really solid and firm. R. flaviceps has a solid stipe, but differs in the other discriptions.

So, unless someone has a better idea, I am going with R. albida — just one with a funny stipe.