Identificaciones de sonnia

Had a great time helping out with the Wildlife Conservation Camp at the Clear Fork Ranch. I talked a bit about iNaturalist, led a mothing program, caught some dragonflies, and talked a bit about plants. Great fun!
These observations uploaded with permission of ranch management.

I'm stumped on these little pink 6-merous flowers. I was thinkning this was going to be some species of Lythrum or perhaps an odd member of Caryophyllaceae like Silene, but I can't match it to anything. Notice that the calyces and stems are glandular pubescent.