You can ask your friends or local photographers for recommendations. Also, check out Texas Highways for the best wildflower locations! (http://www.texashighways.com)
Hopefully there won't actually be snakes where you shoot, but be mindful of that possibility and keep an eye out.
For best results, shoot in early morning or dusk to avoid harsh sunlight, which will cause squinty eyes or overexposed backgrounds. To make a dramatic difference in the quality of your photos, sit your subject with their back to the sun, and use a reflector like this one ( http://www.bhphotovideo.com/c/product/1016048-REG/raya_cr_51_42_5_in_1_collapsible_reflector_disc.html )to add a warm glow, and put a little sparkle in their eyes!
Avoid awkward "squatting over the flowers" poses with a simple prop.
Your model may not be too excited about sitting on wet ground, or get poked by sticks and rocks. You can easily pick up a small crate like this (http://shop.hobbylobby.com/products/wood-box-crate-set-with-antique-brass-handles-550244/) to pose them on. It looks cute and doesn't block or squash nearly as many flowers as a blanket might.