Check out these websites where you can also post your resumes:
http://www.cnmdallas.org/opportunity_501.aspx - Opportunity 501 is a cost-effective method for nonprofit organizations to recruit qualified personnel and to assist individuals seeking nonprofit jobs in Texas:
http://www.txnp.org/jobs/jobsearch.asp - The most significant nonprofit portal in Texas, TexasNonProfits.org provides data that facilitates connections between the 80,000+ nonprofit organizations with the 4,000+ charitable foundations in the state of Texas, major philanthropic corporations and sharing individuals.
www.ajcjobs.com (they have a non profit section)
www.learnhowtobecome.org/volunteer-and-nonprofit-careers/ - Learn how to become...Volunteering and Non-Profit Careers
https://edubirdie.com/blog/volunteer-opportunities - a list of the best volunteer programs for students
https://edubirdie.com/blog/nonprofit-careers - Nonprofit Careers for College Students