unfortunately she doesn't do porn. or at least not yet, anyway. but Amazin Amie has a spectacular booty.
http://dynastyseries.com/wp-content/2009/03/amie14.jpg
http://g1wallz.com/wp-content/uploads/wallz/5795/Amazin Amie 2.jpg
http://www.bigdonmjent.com/documents/AMAZIN_AMIE.jpg
as far as the white pornstars with big asses, i'm going along with what most folks here have said
flower tucci ~ the best of the big white asses imo
alexis texas ~ use to not really dig her, but over the last few months she's really doin it for me
velecity von ~ she's just a lovable do-able naughtly little slut. thank god for that.
naomi russell ~ havnt seen her in anything new in ages, but the last stuff i saw her in, she's lost almost all of that beautiful butt
rachel starr - not as big but definitely the most shapely, toned and perfect ass in porn imo
another non porn white girl with a nice big ass would be ice t's woman, coco
honorable mention: Ricki White