I understand the dilemma now. You created the FAG memorial without knowing she was buried there.
Burial records or burial transfer permits are next to impossible to find especially when a person was buried in 1888. Generally there is no law that requires they are kept. If this is an active cemetery, the owners might have the records.
If not, you can contact the Webster County Genealogical Society, http://wcgsiowa.org/
and/or the Webster County Historical Society, http://billgibbs.net/history/index.html
and ask if they have cemetery inventories. They should be able to answer your church question too.
If she was buried without a tombstone, it might be impossible to find documentation on where she was buried. Successful Searching!