Could be. Or one of the 300 other species of viola native to North America. Really need to see in flower to be sure.

I don't think it's any Viola. Wrong texture. Did the foliage have a smell? Lamiaceae???

Yea, I think it's likely a Mint. I took some new pics of another specimen in that area:

So, I don't think it's a Violet...but probably not Heartleaf Skullcap, either. Which looks more like this when small:

So, still not sure what it is, then?

What's the difference between your featured plant, and the photo of what S. ovata should look like? There's a lot of varience in leaf shapes. Your featured plant has shorter, rounder leaves, but plants with longer, narrower leaves seem to be more common. Other than the leaf shapes, the leaf veining, stems, and pubescence all match Scutellaria ovata. Scutellaria ovata is the only species that resembles your plant, when I do a search of all species in Lamiaceae for Dallas? The link gives ID tips. The rhizomes look unusual. They resemble the edible Stachys tubers that look like giant beetle grubs.https://anps.org/2018/07/11/know-your-natives-heart-leaf-skullcap/

Hmm, so I just took another picture of them blooming...and it does look like it very well may be Scutellaria ovata (Heartleaf Skullcap)?

I grow Scutellaria incana, but my 1st choice was ovata, but the seeds never germinated. There are 3, maybe 4 subspecies. The differences between them is mostly in the flower structure and color. The subspecies found in your area is Scutellaria ovata subsp. ovata. A 4th possible subspecies is Scutellaria ovata subsp. venosa that occurs further north. Venosa is mensioned at the Lady Bird Johnson site, but that species isn't in Weakley's Flora, so it's possibly illegitamate or it was changed or lumped into one of the other subspecies?