When I composed this post about the grammatical errors that characterize certain accents, I was mostly referring to foreign accents. After spending several days down South, however, I realize that the same holds true of regional accents. To me, the most noticeable feature of an American Southern accent is the replacement of adverbs with their adjective counterparts, e.g. "That works real good" instead of "That works really well."
The Wikipedia entry on Southern American English has a more extensive list. The use of "me" and "him" rather than "myself" and "himself" in examples such as "I bought me a new coat" is another that always sticks out to me.
I checked the other entries on North American dialects to see whether my own English---shaped mostly from living in Kansas and California---has any grammatical idiosyncrasies that I've failed to notice. I didn't find any, although I plead guilty to overuse of "like" and "totally". There is, however, a delightful section on the differences in freeway nomenclature between Northern and Southern Californians. It's one of the first things I teach my friends who move here from Los Angeles, and my biggest gripe about the movie "Sneakers", which is set in San Francisco but whose script was clearly penned by Hollywood natives. "The 101", indeed!