Fahim
I daresay it happens occasionally. But it would be a very informal arrangement.
Steven J Pemberton
Not unless the somebody is somebody the typical moviegoer has heard of, and is happy for the movie producers to use their name in the movie's publicity.
There's no market for ideas for stories, for the same reason there's no market for fresh air or sunshine - massive oversupply. Ideas for stories are everywhere, if you know how to recognise them. Anyone who's capable of writing a screenplay that's good enough to be produced doesn't need anyone else's ideas for what to write about, because they already have more of their own than they know what to do with.
Screenwriters do sometimes get brought in to rework or rescue someone else's screenplay, but that's the decision of the producer or director or studio (because they're the ones paying the new screenwriter, not the original writer).
Anonymous
I doubt it. I'm a novelist, but I know a few screenwriters online. Nobody has any shortage of ideas.
So if you have a great idea, you won't get money for it. Even if it's legitimately amazing, nobody wants it for their own work.
bluebellbkk
I daresay it happens occasionally. But it would be a very informal arrangement.
Elaine M
No. Outside ideas are not used, for liability reasons.