But isn't Texas a whole nother Country?

IIRC Texas is the only state in our union that can lawfully secede and go back to being a country. Just going on something my brother told me. Something the effect that Texas would only agree to join if this condition were allowed for it. Any natural born Texan would know the answer to this. Is my brother correct?

It isn't what we don't know that gives us trouble, it's what we know that ain't so - Will Rogers