When researching, it is best to give information concerning the males in the family, a husband, if possible, because early records very rarely give any details on females. You are getting your information from other family trees, which is fine to begin with, but it also is best to continue to look through those trees to get more info to help you pin down locations of where these individuals were at any particular point in time. It is after you locate that info that you start actually looking for records to back it up.
I took a look at the names you give in the Family trees on Ancestry.com, and I don't know if you have a subscription to it, but there are several trees which gives you additional info on the family. Most of them show that couple came out of Virginia, and were married abt 1767 in NC (some say specifically in Orange Co., NC) and that's where they start varying about where Mary supposedly died, some have her in TN or KY, or wherever. One or two of them have parents for Mary as Samuel Benton, d. 1770 Granville Co.; of course, none of these trees provide any real sources for their info, other than copying one another. I doubt, though, that she was a dau/of SAMUEL BENTON, d. 1770, unless someone has some further proof about it, since his will has been transcribed and there was no daughter with her name mentioned. A copy of that will is online:http://www.ncgenweb.us/ncgranville/wills/early-granv-wills2....
As far as any further info, if you know her place of death, I would suggest that you research that area more specifically for any records involving her, for instance, if she left a will, or estate records, you would need to look at that to see what kinds of transactions were mentioned, and perhaps she may have inherited something from a parent, or other close relative which she mentions in her will.