I suspect that every songwriter to some extent has one or more of these types of files. I refer to them as sketchbooks, not unlike what an artist keeps to make studies of interesting people, buildings and landscapes. A musician is of course concerned with other things -- guitar riffs; choruses, verses and fragments of same that tend to fade into oblivion unless you capture them quickly. This is especially true for melodies, which are by nature fragile and ephemeral (at least, mine were).
This is part of a chorus that I thought was pretty; though as far as I know, I never did resurrect it later for a song.