That is a really well fed or gravid ground spider (family Gnaphosidae). Those spinnerets give it away. She's probably species Sergiolus montanus. They're harmless.

Compare:

http://bugguide.net/node/view/415150/bgi...

https://scontent-b-dfw.xx.fbcdn.net/hphotos-xpa1/t1.0-9/10447085_10202168175877720_2293061476821513307_n.jpg