Here are some ideas. A lot of ornamental grasses I'm familiar with top out at zone 9, but these should tolerate your climate with suitable soil and irrigation.

Eragrostis elliottii
Eragrostis elliottii 'Tallahassee Sunset'
Melinis nerviglumis 'Savannah'
Miscanthus sinensis 'Little Kitten'
Pennisetum purpureum 'Princess Molly'
Pennisetum purpureum 'Princess Caroline'

These may or may not exceed 3'...it depends on whose description you read:
Muhlenbergia capillaris 'Regal Mist'
Muhlenbergia capillaris 'White Cloud'

Not really a grass, but there are lots of beautiful cultivars of Acorus gramineus which will tolerate your weather and fit your size requirement.

Juncus effusus is interesting, but may need very wet circumstances to survive your heat.

If can get away with it, there are some running Bamboos in your size range, including Pleioblastus viridistriatus 'Chrysophyllus' and Pleioblastus shibuyanus ÂTsuboi.Â

I second the vote for muhly grass. Muhlenbergia capillaris looks great planted in mass...and is a Gulf Coast native!

Thanks everyone for all these great suggestions. I am not familiar with many of Donn's suggestions but will check them out.

Elaine