Maybe one of the Galinsogas? Can you get a closeup of a bloom?

That's hard. The flowers are just a few mm across. But try this. Blooms are not very symmetrical. Some have petals in a circle, others have petals sort of lined up. The leaves do very much resemble Galinsogas (Quickweed), but the pictures I have of those have a prominent bud in the middle of the petals. These don't. Also, these petals are not toothed.

Calyptocarpus vialis? Creeping Cinderella Weed?

That may be it. Calyptocarpus vialis - Horseherb. Thanks!

You're welcome Dan. It's a new one for me. At first glance, it does resemble Galinsoga. Wikipedia hints that it's not native to Texas, but Nesom believes it was originally ranging into southern Texas. There's also another Galinsoga look-alike in Florida called Synedrella nodoflora. Some of these plants have ridiculous common names Lol.

Calyptocarpus vialis

Looks like Horseherb to me also.

LadyBird Johnson Wildflower center designates it as USDA L48, which mean's it's pretty common all over the continental U.S., but possibly by introduction. Wikipedia actually does say that it is native to South Texas.

I planted 2 four inch pots of it a few years ago. The soil was sandy & it received regular irrigation. Within a couple of years it had spread to cover an area that was at least 300 sq ft. I sold that house last year, it may cover an acre by now. LOL

Yes, the patch that I'm looking at now covers about half an acre. Basically a ground cover that can be used as a lawn. Pretty tolerant of foot traffic. It's also listed as not being invasive, which doesn't appear to make a lot of sense, in that it spreads rapidly. It's drought tolerant, grows well in shade, and hardy to 8a. If it were taking over my lawn, I'd try to get rid of it, but by itself, it's nice. I should add that two years ago we had Zone 6 winter temps, which must have killed it all off, but it came back in droves. Have to assume that if the roots survive, you'll still have it.