Lately, when my Facebook memories come up each day, if there is a story or quote I included in my post that I've forgotten and haven't scrapped those photos yet, I go find the photo(s) on my computer and add info in the 'subject' field.
I have lots of pictures that I don't remember necessarily why I took them or all the details, but I'll include the date and make do with a couple sentences that include what we were doing or where we were. In the below page, I don't remember why we were at my parents' or why I was in that particular spot in their yard taking pictures, but the pictures are so sweet to me and I went with that feeling.