In north texas horse mint - aka wild monarda - is very popular, but it's tall, not a ground cover. If you can get dutch clover to grow - that's a ground cover but it does often take inoculating the soil to get it to germinate. Crimson clover can be seeded in border edges and flowerbeds, allowed to bloom, and re-seeded. Any wildflowers - they do often get tall but tend to be very popular with bees. in desperation and not a good honeycrop, frog fruit is a ground cover that will live in almost any wet sunny location and is somewhat drought hardy and winter hardy. all good things to run by your county extension agent. If you want natives you will have to contact your local Native Plant society probably. Frogfruit is a texas native, and many of the wildflowers I grow are, but I don't know what is native to your area, and your extension agent might. Don't ask a big box garden center.