I keep a note open on my work computer at all times. In it I jot down story ideas. Simple things. Not good ideas, per se. Certainly not substantive ideas. Just ideas.
The kinds of ideas that you think about and then, two minutes later you think, “what was I thinking about?” and never recover it. I write them down primarily so I don’t have to deal with that taste in my mouth of forgetting something without writing it down first, even if it wasn’t worth writing down in the first place.,
But I also keep the list of ideas so that, when I don’t have something I’m inspired to write, I can look back at some ideas, and choose a topic to run with.