Gabion walls of recycled terracotta pots is featured in The Real Rubbish Garden by Claire Whitehouse, an environmentally friendly garden with recycled household materials, at The Chelsea Flower Show 2005 in London.
How to Make Seed Bombs - Recipe for Kids - Love this idea for guerrilla gardening and adding flowers and a lovely splash of color in all kinds of places! Important to not just use ANY seeds but to use seeds for flowers NATIVE to where you live.
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.