Someone gave me a very pretty folder which has pockets in which to store papers. I used it for some vital historical research re:- my new novel, Monday's Child, the sequel to my published e-book, Sunday's Child set in the Regency era. For two days I searched the house for it. I even woke once last night fretting about it and trying to remember the details of the research. This morning when I got up I thought that it must be with all my other files. I returned to the cupboard in which I keep them - sure enough it was there.
The experience is comparable to writing. Sometimes the eye does not see what should be there.