what does he use for identification, if he has no birth certificate? he must have some identification, otherwise he wouldn’t have a driver’s license or social security #.
since you say that someone told him that his mother’s name was virginia and he is 100% choctaw, there was a source of information of some kind. you don’t identify who told him this nor under what conditions he was told this.
as far as his tribal affiliation, you need more clues here. tribal affiliation and heritage are two different topics. this is the website of the choctaw tribe of oklahoma. you might have to look for a texas tribe.
it sounds as if your start is with documents that he might have. maybe he was adopted, i don’t know. you don’t say what has happened to him.
if he was adopted, then you should contact the adoption coordinator in that state and see what records they have of his birth family. ask for post-adoption services. if he was not adopted but lived in foster care, they might have some records also.
you are basically describing a fairly impossible situation and you need more information. finding his tribe is secondary, after finding more information about his parents.
texas vital records are here.
texas adoption records
so, in my opinion, you need to find basic records first. after that, you might be able to pursue heritage information.
suzanne hamlet shatto