I want to believe this is a joke... but it isn't.
A cancer-ridden women who died decades ago left a series of index cards with indeciphierable ramblings on the backs of them to her grandchildren before her passing. Now fully grown, those grandchildren have turned to the internet in hopes that they can get help in solving what they beiieve is some form of code.
My grandmother passed away in 1996 of a fast-spreading cancer. She was non-communicative her last two weeks, but in that time, she left at least 20 index cards with scribbled letters on them. My cousins and I were between 8-10 years old at the time, and believed she was leaving us a code. We puzzled over them for a few months trying substitution ciphers, and didn't get anywhere.
After making the post on Metafilter, parts of the encryption seemed to have been already solved. It appeared to users that the woman was partly writing prayers through her code.
Was she a religious woman? The last As, as well as the AAA combo, make me think of "Amen, amen, amen." So extrapolating -- TYAGF = "Thank you Almighty God for..."
It would make sense to end with "Thank you, Almighty God, for everything, Amen - Thank you, Almighty God, for everything, Amen, Amen, Amen."
Our Father who art in Heaven, hallowed be thy name... etc etc etc
Check out the entire thread here to see if you can figure it out!