It sounds like she was white, since most black people didn't have last names in 1841. That and the 1841 birth year mean she wasn't the black lady born in 1872. I noticed I didn't identify where I found those two people - it was on the LDS 1880 census transcription.
I looked again. This looks like them:
NameRelation Marital Status Gender Race Age Birthplace Occupation Father's Birthplace Mother's Birthplace
V. MAYFIELDSelfMMaleW40GAFarmingGAGA M. MAYFIELDWifeMFemaleW37SCKeeping HouseSCSC P. MAYFIELDSonSMaleW7ALAt HomeGASC W. MAYFIELDSonSMaleW5ALAt HomeGASC H. MAYFIELDSonSMaleW4ALGASC R. MAYFIELDSonSMaleW1ALGASC
Source Information: Census Place Alexandria, Calhoun, Alabama
An appalling number of Southerners went by their initials in 1880; a mess of Northerners, too, but not as much. If you look for "R. L. Smith" you get roughly half the men named Smith who were born after 1861 in what had been the CSA.
The age isn't exact, but it often wasn't. Mahala shaved 2 years off for vanity. I'd be willing to bet 10:1 this was her. It isn't much, but it is a clue.
I looked up roughly 850 of my individuals on the LDS 1880, over a period of 6 months. When I say I'd be willing to bet this was her, I'm speaking from experience. I'm also tooting my own horn, I know. I have my limits, but I've spent a lot of time looking for people on the LDS 1880. I found this family by looking for anyone named Mayfield in Calhoun County.