I have never heard of such a thing being done. I can believe it though. Sailors were/are quite superstitious.
Better question, if you did put something that weighty on a rail, how the hell did you not derail the train? Have you ever seen a coin recovered after this? I imagine it would be quite smooshed. My grandpa and I used to put Lincolns on the track and they would go flying. It was a fun adventure to try and find them after. I put a dime on once, but I never found it. Nowadays, putting coins on tracks is illegal and you'll get in big trouble if caught.
I imagine I knew about this because I saw it in The Numismatist or a show exhibit, and the smooshed look of the OP's coin reminded me of what I saw.
Since no one else is saying anything, I believe it's a 1798 large cent. But I can't determine the variety.
I was thinking the 1798 S-164 based on the angle of what appears to be the stem of the wreath and the A in America. Most others with similar traits are earlier NC coins. In fact, in trying to determine the variety, I realized that this is a pretty rare trait in the earlier coins and quite a few of them are NC coins which is a good quick reference tool for myself to try and cherrypick a couple of these.
I was first thinking 1796 Rev. of 97 was a possibility, but couldn't find a smoking gun one way or another.
I had it narrowed down to large cent between 1793 - 1807 because the "100" of the "1/100" decimalization is very visible on the reverse photos and it doesn't look like a Flowing Hair type (at least I don't think it does). But I hadn't really narrowed it down much further than that. That obverse really took a beating and is mussed beyond recognition.
Thanks to all of you that took the time to post a reply. I do so enjoy trying to identify some unknown Coin or thing. And since no one has posted for a week I will give my findings, and of coarse it is all just speculation. The faint outline of a bust on the Obverse and the location of an "L" at the top rear of the head makes me inclined to say it is a Draped Bust between the dates of 1796 -1807. My oldest US coin.