Small metal object with clip on top. Clip spins around the object body and can be attracted to a magnet (so made of steel probably). Object body does not react to magnet (so made of brass maybe). Cone shaped tip seems to be made of some kind of plastic.
Found this in my back yard, probably from something I was working on, but it doesn't look familiar.
What is this thing? (Identification may help me fix something I don't know is broken!)
As others have already said. Thats a needle valve from a carburator. Theres no question about it. It also isn't something that falls out. Someone did some lawnmower repair and either was annoyed when they lost it or just pitched the old one in your yard when their parts kit came with a new one. There's probably not much point in saving it though because they're dirt cheap and easy to get. Whoever lost it has almost certainly replaced it by now because without that little needle the carburator won't work and will start pouring gas everywhere.
Thanks!