Check out this Artist: 

Andy Goldsworthy  https://www.boredpanda.com/land-art-andy-goldsworthy/?utm_source=google&utm_medium=organic&utm_campaign=organic

He does some amazing natural artworks using things we can find out side.

Here are some other Ideas for making Art Outside.

Rock Towers

Build Rock Cairns by stacking and balancing different sized rocks on top of each other. Mr. Blake has posted some of hi creations on Class Dojo, maybe you saw those. Big rocks are easier to stack than small ones, but they are heavy so be carfeul.

Temporary Graffiti

Use something wet, like a stick or rag to create temporary water paintings on concrete or another dry surface.

Weave me Alone

Sit down and take a quiet moment to create a weaving using sticks, leaves, or other fibrous natural material. Remember you need to make a loom with warp before your weft does the over-uder-over-under pattern.

Will it float?

Make a boat out of found objects. Will things other than wood float? What about paper? Plastic? That piece of candy wrapper or an empty soda can?

Painting with Rocks

Organize rocks by color then create a pattern or design

As with all activities, get your parent or guardian permission and if possible supervision.