I'm pretty sure that in the novel Gone with the Wind, Prissy said "Lawdy." Not sure whether Margaret Mitchell had white characters using this expression as well. I can check. I've never heard "Lawdy, laws" but I haven't spent much time in the South.
I had a typo which I've corrected--I meant that I think everyone said "lawdy." Though I also think they said "laws," and so on.
But I'll continue, just for posterity--Prissy does say "lawdy" in the movie, though she does not in the book. About whether the white characters say "lawdy"--they don't. But I've never found Gone with the Wind
, book or movie, a historically realistic representation of, well, anything.
Mitchell writes the Prissy's speech thus:
Fo' Gawd, Miss Scarlett!... Ah--Ah--Miss Scarlett, Ah doan know nuthin' 'bout bringin' babies. Maw
wouldn' nebber lemme be 'round folkses whut wuz havin' dem.
Scarlett's pronunciation of "Lord" would have been pretty close to if not the exact same as "lawd" (though in the book she thinks, "May the Lord damn Prissy."). Yet she replies thus:
You black liar--what do you mean? You've been saying you knew
everything about birthing babies. What is the truth? Tell me!
For the most part Scarlett's written idiolect does not reflect any accent, and the reader is meant to imagine some charming Southern drawl, which, opposed to Prissy's idiolect, would have reflected a white linguistic superiority. So we're talking about linguicism and racism. We could rewrite Scarlett's words to reflect her actual speech. While it would be a little different than the slave dialect, it would resemble the slaves' speech more than Mitchell would have been comfortable with.
So anyway, I only meant to question the word's origin or even mental association as a slave word. I think it's only that people would have been more likely to write it phonetically as such.