Thanks so much, Mary! Yes,everything I found is in the profiles: US Census for 1850, '60, '70, and '80 (every available Census in her lifetime), her FindaGrave (which doesn't give a first name), and her son's Louisiana Death Record, which does give her a first name. No two records have the same spelling, LOL.
The family lived in Donaldsonville, so the Ascension church is the most likely one. If you are familiar with the red Diocese of Baton Rouge compilations, I can narrow it down for you considerably. The marriage record, if it exists, is in Vol 11 (I have Vol 10, and it's not there; she got married before Vol 12 began). If we can believe her gravestone inscription, she was born in 1841, so her baptism record would be in Vol 6.
ETA: Eddie found a description of the marriage record: Donaldsonville, Oct 1869. Definitely Vol 11.