Rivet?

[Mchad34]

Find a lot of these at a late 1800's site. This is a view from top, bottom, and side. I have seen them in a picture on this site before, but the person posting didn't know what they were either. If it is a building material any idea on the dates they were used?

 

[kuger]

Yes,rivets used on leather.....still used today!