Mr. Smarty Plants is glad that you enjoyed your visit to the Ladybird Johnson Wildflower Center. Please come again soon.
Growing Texas Mountain Laurel Sophora secundiflora (Texas mountain laurel) from seed is an interesting project that can be frustrating or rewarding, or both. My first caveat is that the seeds are toxic, so if you have children involved, use caution to make sure that none of the seeds are ingested!
I'm providing several links with information that should help make this project a success. The first is the NPIN Database Page for Sophora secundiflora (click link above). Under growing conditions, you see that the plant prefers, among other things, full sun and well drained alkaline soils with a pH<7.2. The paragraph on Plant Propagation describes procedures for scarifying the seed and conditions for planting.
Here are some other links with a brief description of contents:
Plantanswers.com good description of plant, and germination procedures
Bob Harms, UT Austin good discussion on germination
Paul's Blog good general information, use of limestone gravel to raise pH
Texas Gardener (scroll down to Mountain Laurel) talks about growing the plant in East Texas
Aridzonetrees.com good general information
In summary, if you give the plants full sun, provide them with well drained alkaline soil, and don't over water them, they should grow in Harris County. The hardest part may be getting the seeds to germinate.