Desmanthus virgatus does look a lot like it but most of the Desmanthus are listed as shrubs. This plant was only a few inches high and spreading like Mimosa strigillosa, although it was on the side of the highway that gets mowed. I was able to get some seed so it think I will have to grow some this year and see what the true form will look like. Maybe that will help with the ID.
Thanks for all the suggestions I think you are on the right track with Desmanthus.
