In Kill Bill Vol. 1 a whole animated mini-film is dedicated to the backstory of O-Ren.
In contrast, I didn't notice anything mentioned about origins of Vernita, even though they both were assassination targets in the movie.
In Vol. 2 we even get some details about pasts of Budd (Bill's younger brother, possibly went through similar training), Ellie (was trained by Pao Mei, he gouged her eye, she poisoned him) and Bill (grew up with a mexican gangbanger for a father substitute, has been collecting father figures, studied under Hattori Hanzo and Pao Mei).
Is there anything known about Vernita?