Mary Elizabeth Fitzgerald (O'Brien) - Any sources at all regarding this person?

I see that on FamilySearch dot org, someone has her combined with a Mary (O'Brien)FitzGerald who is allegedly buried in Westminster Abbey. (It's obviously not likely that a person who died in Orange Co. VA during that time period was buried in Westminster Abbey.) It's difficult to evaluate any of this because there are no primary sources attached to either person at either site.