I don't know if you'd consider it specifically Texas-themed, but I have to say I really like some of the boot quilts that I've seen recently (especially if it's going to made for a female).
Here's one example:
http://www.jubileequilting.com/Galle...oot-quilt.html
The fabric variety obviously makes that quilt sing - and makes me smile each time I see it.
You could always but the frog on the boot.
Here's another version (pattern):
http://www.chickadeecharms.com/westernpatterns.htm
If you do a Google search on "boot quilt" and click on IMAGES, you'll see many others for more ideas.