Centaurium texense (Griseb.) Fern.
Lady Bird’s centaury is a low-branching plant three to seven inches tall. The flowers can reach a diameter of 1/2 inch, while the leaves grow to 3/4 an inch long. Lady Bird’s centaury is found in dry, open, grassy areas of the Edwards Plateau and South Texas Plains. It flowers approximately from May to July.
Click image to enlarge.