Elf house on a tree! That would be cute in the garden, especially in the tree over grown with ivy. How about some battery tea lights in the windows during outdoor parties. I hear the fairies/elves whispering "home school project" in my ear.
Put a door on a tree. Tell the neighborhood kids leprechauns live in the tree and that they only come out after it rains and when there is a rainbow in the sky so they can find their pot of gold at the end of it.
Fairy Garden Tree Stump Stool is perfect for fairies and full-grown people alike! Crafted to resemble a real tree stump, it makes the perfect fairy garden accent, but it can be used as a table or stool for humans, too :) - Fairy Gardens