Your stories? After all, it can’t hurt to tell us now.
To get things started, I’ve been yapping to friends for years about an idea that utilized the same plot twist eventually used in Gone Girl.
(If someone has already started a thread along these lines then it just proves my point)
I invented boy meets girl, boy loses girl, boy gets girl back
A young adult novel retelling Count of Monte Cristo in a modern setting with a female protagonist. Oh.
Plot twists? Are there any that have not been done, many times? Original plots (or even original seeming) are not all that important in literature. Shakespeare blatantly stole most of his.
It ain’t what you do, it’s the way that you do it.
A friend of mine is an aspiring screenwriter and one of the irons in the fire is a story about a reluctant Santa Clause. She’s been bouncing ideas off me and I keep saying “Hey, that sounds like…” She has avoided seeing most of the recent, popular Santa Clause movies because she didn’t want to just recreate them, and… she’s recreating them anyway. Fortunately, she has some other scripts she’s working on which aren’t as unintentionally derivative.
[raises hand]
Years ago 
It wouldn’t be the first time that someone [del]stole[/del] borrowed that plot. Stephen Fry did so, for his novel “Revenge.” (And apparently he didn’t even realize he was doing so even as he was writing it.) But the story wasn’t even original to Dumas; he read the story in another book.
(BTW, one of the television networks is adapting Les Misérables as a drama series.)
I’m a fan of Eric Flint’s 1632 series. There are now a lot of published short stories in that “universe”, done both by Flint and his co-authors. But there are also sanctioned stories by first timers, and a set of rules on how to submit such a story.
I got to thinking of what a German downtime hunter would think the first time he saw a racoon, for surely a number of them must have come through with the Ring of Fire event. I looked up all kind of info on the critters, and even found out there are racoons in Europe now, doing very nicely, the descendants of two populations, one which was deliberately freed, and the other accidentally.
Then I read the story “Birdwatching” which is basically the same thing, with uptime birds getting established in the Grantville area in Europe.
If I wrote my story now folks would think I was a copycat. 
Happens all the time. Four or five years ago I had an idea about a bike courier who is carrying something that some bad guys desperately want, and that as the courier knew the city well, he’d “parkour” his way around the alleys to get away from them. Then the Premium Rush trailer came out. (It’s a pretty good movie, except the last half hour loses all momentum)
I also have this idea about… hmm, well I’m not going to reveal this idea, it’s still a good one, but a lot of the set-pieces I imagined ended up in the (awful) Paul WS Anderson Three Musketeers movie.
Two of my friends had ideas for a Red Riding Hood movie independently and at the same time, and just before the Twilight-y version was made.
For years, I’ve been asking every programmer I know to work with me on making a faux-retro zombie apocalypse takeoff on The Oregon Trail. I can’t find it at the moment, but I recently saw somebody did exactly that (they actually did it more on-the-nose than I would have, but still close enough).
The Organ Trail, you mean?