Yes, I have heard Reba speak. I think she cultivates that southern accent in her speech and song, with some exaggeration, for effect.

I was 'borned', as they sometimes say, in the great South. I have deliberately made an attempt to 'shed' myself of the accent I learned as a child. People still recognize the vestiges of that dialect with some of the words I use. Some of my dialect is ingrained and probably can not be completely eliminated. I could cultivate my southern pronunciations to make a song like "Y'all Come", for effect, by drawling the "Yaw", but chose not to do so. I must admit that the following phraseology "don't" quite have the same effect as Y'all:

"You all come, you all come, you all come to see us now and then…"

I don't 'sang' it that way neither. That reminds me of another 'sanger' that I can't listen to: John Anderson and his song "Swingin'" where he sangs "and we wuz swangin', swangin'"

I admit to liking, and sometimes using, nonstandard English such as the stuff my grandfather (and some Mudcatters have) used. Examples like: Yourn, hisn, hern, ourn, and theirn. These substandard vulgar forms of pronouns are humorous when used as parodies or in written style reflecting hillbilly dialects documented in books like the Foxfire series. Shucks, sum of muh kinfok cum frum dem deep dark hollers down yunner in Tennossay.   

I also like the many novelty songs where nonstandard English and accent are used to great effect.

'Life Gits Tee-Jus Don't It' and 'Down On The Farm' by Walter Brennan (and more of his tunes).

'Wildwood Weed' by Jim Stafford

I spent tuh rayst of that day an most of that nite a'tryin' ta find my brother Bill,
Caught up with em 'bout sex o'clock tuh nayxt mornin', naykid, swangin' on the windmill
He sayed he flew up 'air,
I had tah fly up an git em down,
He wuz 'bout haff crazy

Y'all come back now, hear?


'Mr. Custer' by Larry Verne.

Look at them bushes out there
They's a'movin' and they's a injun behint ever one
They's a redskin a'waitin' out there, a'fixin' to take my hair

Most of the mainstream (not novelty) modern country music, with its exaggerated, fake-accented enunciation, is just not what I care to listen to. I usually turn the radio dial when I happen on it. C&W music before the mid- 1970's is some of my favorite.