Anyway you're in a good area for artifacts being on the SG river. That whole area around the SG produces also...
Looks like a lot of rocks and dirt, nice blue skies. In all seriousness I would keep looking there. Looks like a nice core or scraper in your hand.
Good advice from a fellow Texan.
More good advice. I agree that you have found a core. Keep looking there. Texas has some of, if not THE best artifacts and material in North America.