Possibly a Gypsophila. Or a relation. Got any with flowers?

Here's a view from the top.

Yep...I have it inundated in my backyard as well. I live just south of Austin, TX. I have searched on line for hours tonight and a few other folks have posted this weed pic on Dave's Garden forum and on another site and neither one of them got answers either. It almost looks a little like a combination of a type of doveweed and goosegrass combined. I am thinking that it is actually a cross between Bermuda grass and a weed or wild Bermuda grass...if that is even possible. I haven't seen any flowering on these weeds. They are in approx 5-10 inch clumps. Very sturdy and easy to pull up with a little water in the ground. I haven't tried many chemicals yet. I have only spot treated with Weed B Gone. I am pulling them as well. I think that my Bermuda grass is almost gone because of this terrible weed. Once I pull it all out, I will probably have to re-sead some Bermuda.

Just adding a pic as well. (I am new to forum posting...sorry)

Probably slender aster. Wait for it to bloom in the fall.

Here is a link that might be useful: AggieTurf Texas lawn weeds--Slender aster

Aster looks correct to me as well.

We live near DFW airport. This weed has been aggressively invading our St Augustine lawn in the front yard. I brought samples to Marshall's Grain in Grapevine. A worker there took one look and said: Fall Aster. I'm not 100% convinced of the ID, but no one has offered a better match yet.
We have been pulling them out, one by one. They seem to choke the St Augustine sucking up nitrogen from the soil. This past weekend, I heavily spread corn gluten meal--not as a pre-emergent, but to return nitrogen to the soil. We've pulled literally hundreds from a small, 1000 sq ft front lawn.

Check out this report on "Slender Aster"--it looks very similar to the pics on this page.

Here is a link that might be useful: Weed problem - Slender Aster

Yup. Slender aster. First time in the lawn. supposed to be controlled with broadleaf killer, but is tough to kill off.

https://www.lawndork.com/weeds/slender-aster

ricstr, the common name Slender Aster refers to 3 different species, Eurybia compacta, Symphyotrichum divaricatum and Symphyotrichum subulatum. Eurybia compacta,(Aster gracilis),doesn't occur in Texas. Your aster could be Symphyotrichum subulatum or Symphyotrichum divaricatum, which is another species of weedy lawn aster. The above link says the weedy, Slender Aster is Aster gracilis, which is now Eurybia compacta. That's not correct. Symphyotrichum divaricatum is commonly called Roadside Aster, but also Slender Aster. Symphyotrichum divaricatum was formerly Symphyotrichum subulatum var. ligulatum. Symphyotrichum divaricatum is easily confused with Eurybia divaricata, a totally different species. Compare your plant to the 2 species in the links below. They are both annuals, and you can get rid of them by not allowing them to drop seeds. It's very confusing with 3 species having the same common name. The photo in your link is really Symphyotrichum divaricatum, and not Aster gracilis,(Eurybia compacta). Normally the species names of old genus name Aster, remain the same except the end changing from us to um. Symphyotrichum divaricatum and Eurybia divaricata have both been named Aster divaricatus at different times in the past. When the most recent change was made Symphyotrichum divaricatum was called Symphyotrichum subulatum var. ligulatum, and it was elevated to species status.

https://keyserver.lucidcentral.org/weeds/data/media/Html/aster_subulatus.htm

https://www.kswildflower.org/flower_details.php?flowerID=280