Volunteer through WWOOF
Camp Tonkawa is part of the WWOOF-USA program.
From their website:
"Worldwide Opportunities on Organic Farms, USA (WWOOF-USA®) is part of a worldwide effort to link visitors with organic farmers, promote an educational exchange, and build a global community conscious of ecological farming practices."
You can learn more about WWOOF (and sign up, if you like) on their website: WWOOF-USA®