Thanks for your questions about planting a pollinator/monarch garden. In addition to the information on our website, Monarch Joint Venture has some great gardening resources.
Texas plant list: http://monarchwatch.org/garden/plant-list-tx-monarchwatch.pdf
Check the BONAP maps to determine what milkweed is native to your area. Light green counties are where that species of milkweed has historically been found. http://www.bonap.net/NAPA/TaxonMaps/Genus/County/Asclepias