The library has some wonderful reference books on Southern Culture, including the following:

Encyclopedia of Southern Culture REF F209 .E53 1989
The New Encyclopedia of Southern Culture REF F209 .N47 2006
The South REF F209 .S68 2004

Also, if you go to the library catalog and do a keyword search for  "southern states" and language" there are some good books---- for example "whistlin' Dixie: A Dictionary of Southern Expressions"

There are also some books on the southern language in eBooks-- again, do a keyword search for "southern states and language" (be sure it is a keyword search and not full text). Some of these books are very scholarly--so you may need to take some time with them to find what you want in them

In the Gale Databases, you can find some good articles by doing a basic search for "southern states and language" and clicking on the "subject" box.  Be sure to look under all the tabs (magazines, journals, etc)