the pic is not too clear,

but if it is in a garden, it could be some starved Caryophyllaceae, something in the Dianthus family

were there buds at the tip of the stalks?

the blue-is tint would fit

OK, it just bloomed with these ~dime-sized flowers! So, this should help, now!

I'm guessing it's actually some type of aster?

Appears to be a Symphyotrichum species.

Just a point about the Caryophyllaceae suggestion. They’re not alternate leaved so, even without the evidence of the flowers, this plant could not have been a member of that family.

Flora, I also thought that but then noticed on the Go Botany website the following:

Species in the Caryophyllaceae are mostly annual, biennial or perennial herbs. The stem has swollen nodes at the points of leaf attachment. Leaf arrangement is mostly opposite, though alternate and whorled leaves do occur in some plants of this family.

https://gobotany.nativeplanttrust.org/family/caryophyllaceae/

I have not searched other sites for verification.

My reading says mostly opposite and occasionally whorled. Other than your source I found one which said ‘very rarely’ alternate. Many sources say only opposite. So while perhaps not strictly accurate, ‘not alternate’ appears to be a pretty good guideline. (I deliberately said that, rather than ‘opposite’ in order to cover the whorls.)

I haven't personally seen any of that family that are not opposite.

Possibly the roadside aster (Aster exilis/divaricatum) currently blooming in much of Texas.