I'm pretty sure this is a Bradbury story; I read it in grade school, a short one about a guy who sends an editor a manuscript, but the editors accuse him of plagiarizing a "famous" author that the protagonist has never heard of. He asks the editors to name even one story that the famous author (whom he's supposedly plagiarized) has written, but no one can. In the end, the guy thinks he may actually be the author they're thinking of, even though he's never published a work, because he's either time travelled or had some weird link to the famous author. I'm a little shady on the details about the protagonist's connection to the other author, but I think that's it. Does that sound like Bradbury to anyone? I'm having a devil of a time with it.
It definitely wasn't quid pro quo...there's no actual time traveler, just an author who suspects time travel or psychic connection with the famous author for whom no extant literature exists. I thought it was Bradbury but if the "Bradbury meter" is that low, I'll have to redirect my search. But thank you for taking the time.