Cupcake cake with owl pops in the tree use your own recipe for the cupcakes and then add green food coloring to the frosting you are making the leaves in the tree. The chocolate frosting for the trunk of the tree. Make owl pops and stick them in randomly.
Pumpkin in a lace stocking. I've planted a bunch of mini white pumpkins. White lace stockings on them might be a nice outdoorsy Autumn touch. Inexpensive and kinda unexpected. These might be cute on the outside tables under the arbor too.