We call them bony piles. They did have one very good use they kept the ATV kids off of my farm fields. Sadly they are becoming a thing of the pass as many are now being reclaimed.
Now for John Henry, it is my understanding that was a very popular name during that era. So the fact is that there were probably several men with the name of John Henry working as drivers during the construction of the tunnels.
I would like to believe there is some fact to the story it just makes it more interesting that way.