Does anyone know how to make a realistic-looking staple in photoshop? I've search about 15 pages of Google and am not having much luck.

Making one from scratch? The first thing I think of if you need one is to simply do an image search for one to modify. Or, find one and do your best to re-create it.

There could be a tutorial for making a staple in PS, but I haven't seen one.

Download an image of a staple and erase what you don't like :D