Billy Bob has an accent?
Sampiro, I’m sorry about your problems, but I still don’t understand what you mean by “white trash” roles. Are you talking about poor people or country people or what? When I think of “mountain women,” I think of really hard working and strong women – often very creative in making their own coverlets, soaps, clothes and musical instruments.
I wasn’t gonna post to this thread, because when I noticed it, there were already enough replies, so I thought that my first choice must’ve been mentioned. Bot to my amazement, nobody’s claimed Woddy Harrelson yet.
Although I’m still not sure if the OP wants actors who are always cast as WT, or does an aamazing job in portraying them, or if the search is for WT who are good actors.
I still think Woody is the man.
Only one I can really recall by name is Owen Wilson. He doesn’t usually play white trash characters, but you can sure plop him into a Louisiana trailer home and he’d fit right in. 
I accept your apology, though I’m not sure how you know about my inability to housetrain my dog or my carpal tunnel syndrome (my two most pressing problems at the moment).
“Whitetrash roles”- characters of limited intelligence, intellect, or education, don’t have overdeveloped senses of hygiene, have had brushes with the law and various social agencies, list “Jerry Springer Show Appearance” as a source of income some years, consider mullets to be viable hairstyles, never saw a happy ending when they weren’t holding a bag of popcorn and people whom generally if they were moving into your neighborhood you’d start by signing a petition and if that failed you’d move out.
I nominate the entire “Raising Arizona” cast!
Burl Ives… watch the Big Country and then Cat on a Hot Tin Roof.
I also love the trashiness of Susan Tyrell. Check her out in Richard Elfman’s The Forbidden Zone.
I’ll nominate Tim Blake Nelson from Oh Brother (and other movies, including The Good Girl), and Dwight Yoakam (Sling Blade).
I think the Bundy’s fit the bill.