According To Title IX

"No person in the United States shall, on the basis of sex, be excluded from participation in, be denied the benefits of, or be subjected to discrimination under any education program or activity receiving Federal financial assistance."

However boys are not allowed to play volleyball in Texas schools, but girls are allowed to participate in boy's sports (football, baseball)

To make things worse most Texas schools do not offer boys teams for what is commonly considered girls sports in Texas. I have friends at school that would be willing to play on a boy's volleyball team if schools in Texas had them

There are also hardly any volleyball clubs in Texas that allow boys to play.