I picked up another leaf today. It’s from some kind of maple, I think. The topside is brown and shiny, but the underside is bright white, and feels soft and rubbery, like the lining of a dishwashing glove. It also has a perfect autumn-woodsy smell.

Update: After doing a little reading, it’s probably a red maple leaf (Acer rubrum
), or maybe a red-maple/silver-maple hybrid.