This creature is a female grass spider from the genus Agelenopsis. Grass spiders build a horizontal, sheet-like web with a small funnel-like tube off to the side, where the spider waits for prey to fall into the web. Once the prey has been subdued and bitten, the spider drags it back into the funnel to eat it in private.
This particular spider has made a large sheet web in some borage plants in my back yard. I check on her every day. She is one of the largest grass spiders I've ever seen -- her body is almost 3/4" (19mm) long. Grass spiders usually live only one year, but this one is so large so early in the year I have to wonder if she somehow survived the frost last winter.
Most of the spider's eight eyes are visible in this pic.