I had gotten some oak leaves a while back, but I had to get them from a park not my neighborhood...
My neighborhood has some maple trees and I found that you can use maple trees as well, I found some leaves to make a pile. A few have SOME color to them still, can I still use those?
Lastly, there's a kumquat tree right outside my apartment, it drops brown leaves quite a bit. Can you use those in an aquarium?
Here's pictures of them: