What is the name of the pin that holds a toilet seat-and-lid hinge together?

The lid on my toilet seat slammed down one time too many (I found this site by searching for the answer to that problem, which I had kluged by putting a bungee cord around the tank to hold the lid up while cleaning the bowl) and sheared off the pin around which the seat and lid and bolt extensions rotate. It’s a piece of opaque plastic (acrylic?) and probably costs about a dollar, so I don’t want to buy a whole new seat & lid combo just to replace that piece.

I intend to use the brilliant solution I found on this site (rotating the hinges 180 degrees) to keep this from happening again, but in the meantime I’d rather not send the seat & lid combo to the landfill for lack of a tiny piece of plastic. Any suggestions welcome.

To clarify for the helpful souls who responded so far: I do not want to replace the hinges if I can repair them.
I’m not sure what the stainless steel bolt and nut refer to. The piece whose name (and buying site!) I am looking for is a small cylinder of plastic/acrylic/manmade whatever. There are no bolts or washers or parts that stick out. Just a smooth cylinder. Sorry that I wasn’t clearer 🙁