Hand stamping:
If you want to learn how to do hand-stamping, using copper washers from the hardware store is a great way to get started.
Unless your stamps are really tiny, you'll only get partial impressions on your washers - but that's okay! In my artistic opinion, this gives you a beautiful abstract or rustic pattern on your jewelry.
It's harder to make a "mistake" when you're creating an abstract stamped pattern this way, and after a little bit of antiquing, patina, and polishing, you have a beautiful copper jewelry component that you can use to make earrings, bracelets, pendants, and even rings.
Using copper washers for hand stamping helps you learn how much pressure to apply and how to get a good impression for your stamps.
You can also play with designs and patterns without too much fear of "messing up".