"Textured Painting - Natures Paint Brushes" This is not just art, but art in nature! Go on a nature walk to gather 'schtuff!' Then use what you gather to create art or As art!
A fantastic outdoor art idea that makes great use of loose parts found in a forest: clay faces on tree trunks! My son loves the funny faces people put on trees, now I can let him make his own :)
Fancy Stick Crown - a craft to go along with the Julia Donaldson book, Stick Man - inspired by nature, created for the imagination
Amazing outdoor art: Green man tree gargoyles from the Just So festival