Oh, I just remembered another one!
I was in Boy Scouts when I was a kid and we would collect patches from different events we would go to. When you went to special event camp or whatever you would get patches for that event or camp. Then you could use these patches to trade for other event patches. There were all different kinds of these thing and they were all unique. Different sizes, shapes and colors.
I went to a National Jamboree one of the years I was in Scouts and ended up with patches from all over the world after that. I ended up with a special vest that was covered with these patches that I could wear with my uniform.
They would something like this:
This is actually the patch from the Jamboree I attended
Here are some other examples of the different types
Council Patches
Summer Camps
Order of the Arrow Pocket flap patches