I saw this plant when I was out on the Barton Creek Greenbelt on Friday but didn’t know the name, so I asked Mr. Smarty Plants at the Wildflower center.
As usual he (actually she) knew and sent back the answer. It has several common names including silverleaf nightshade and white horse nettle. Latin name is Solanum elaeagnifolium. Here’s a link to the full description.