Just the other day, I took a trip to the local library to find the second book to the Septimus Heap series. I, of course, found Angie Sage's books fairly quickly, and although they had many of her books, the one I wanted was not on the shelf. Naturally, I asked the librarians to see if it was checked out. It wasn't.
I informed the lady at the counter that I had looked and it wasn't there; she responded by telling me to look around, because people don't always put them back in the right place. A little disheartened, I went back to look again (I had already looked around the nearby shelves, duh). After not finding it, I went back to the librarians for help. Instead of helping, they shrugged and said it could be anywhere. I left, rather annoyed by their lack of help.
However, the librarians, were interesting characters, and a version of this scene has already made it into my next story with Damian. I have changed many of the details and spiced it up a bit, but the entire scene is inspired by this short interaction.
Your experience doesn't need to be Hollywood material. Just the smallest interaction, large enough to catch your attention, but not much more than that, can turn into a scene in your book. Take notes, make a voice memo, or just tell someone about it, and you will be able to get it down on paper. Embellishing the experience into an interesting scene is what makes you a writer.
And no ... I still have not found the second book to the Septimus Heap series.