I think this might be dead brown recluse, loxoceles reclusa
It was alive. I froze it so I could get a better picture.
It does have the recluse mark. I was just reading about how to collect insect and spider specimens for study. The National Wildlife Federation says they believe freezing is the most humane way and least damaging way to do it. I was surprised that the NWF outright endorses killing some wildlife for educational purposes. The NWF Field Guide To Insects And Spiders of North America by Athur Evans is a great book for just twenty bucks. 500 pages. It has most of the spiders that Spider ID gets photos of from Canada and USA.