This is a very common wolf spider in California. These spiders make shallow holes under rocks or logs. Wolf spiders are not exactly harmless because they will bite if provoked. But as far as spiders go, they are good to have in your world. They consume many insect pests that would otherwise harm your environment or home. And they are a rather docile spider and fun to observe.

The males are one-third smaller than the females, having more hairs on the abdomen and darker markings.
 

Left - She awoke from her refrigerator induced stupor and tried to get away from my camera. She was sluggish for only a minute after being released from the cold container. I had to act fast but did chill her down a few times (5 minutes in the fridge).  Right - She emitted a  drop of purplish fluid after the third session and did not recover. In this image you can also see the eight eyes clustered on her face. I've read that even with eight eyes they don't see very well, but I can't confirm that.