You could play Top Tree, a game where you see which tree is the most stunning over the Autumn period. This could involve taking photos of them, and if you play with different people, you could upload them to a central place (e.g. a Facebook group), print them or email them to each other.
Edit: This year I’m using the colours of trees to remind me of the beauty of God, the beauty of transition, as God takes us from one season to another in our lives. What do the trees remind you of?