Ask Mr. Smarty Plants

I see your question! - The Bauhinia lunarioides (Anacacho orchid tree) is a lovely tree that is often found in Arizona and can be grown quite successfully.  Looking through the list of Native plant suppliers in Texas and in Arizona - I found three that offered the Anacacho Orchid  - Arid Solutions in Phoenix, Natives of Texas in Kerrville TX and Madrone Nursery in San Marcos, TX. However, all of these appear to offer plants in pots rather than seeds.

Sweet Briar Nursery & Gardens in Belton TX showed up when I looked specifically for seeds, and lots of web postings from enthusiasts in Native Plant groups.  Have you considered approaching your local native plant society groups?  I know the folks around here will be pleased as punch to offer seeds to a new person coming to their meetings!

 The Arizona Native Plant Society seems to have an active website and the Desert-tropicals website mentions a Society local to Gilbert. You might want to contact them.

 
Bauhinia lunarioides

 The Wildflower center's nursery manager [AKA "Nursery Overlord"], Sean Watson recommends that if you obtain the seeds and want to start them, that they be nicked or scarified with a metal file until the endosperm [the white part] is exposed.  Be careful not to go any deeper or you will damage the seed.  This is to encourage relatively prompt germination, otherwise the seeds can take considerable time [like years] to start.