I always try to jot them down in my journal, but once I do, I'm never really sure what to do with them. I try to find ways to incorporate them into what I'm writing, which doesn't usually work. So they sit in my journal until I stumble on them again and still don't know what to do with them.
I've sort of given up on trying to find homes for these scraps of misfit words. Instead, I continue to collect them as writing exercises, pretending that the people I see on the street are writing prompts, or that the ideas are simply meant to get my brain going.
Since making that change, I've found the scraps come more frequently, and I don't feel as bad about leaving them to linger in a journal until eternity. Maybe someday I'll have a story that would be perfect for the man playing the violin as he walks his son home from school (true story), but until then, he's content.
And so am I.