This grass armchair featured on Treehugger is one of the coolest green ideas we've seen. It's a self-assembled chair, including a 14-piece corrugated cardboard frame and a package of grass seeds. After finding the right spot (remember that you won't be able to move it later), filling the cardboard structure with soil, and a mere 10 days, you'll have yourself a grassy chair.
We spotted it on Ready Made, whose editors call it "an idea they wish they'd thought of," a recurring sentiment that we can totally relate to. It seems that the biggest trick is finding a place for it.
Purves & Purves, a furniture design shop in the UK. With such little weight to this flatpack, don't let overseas shipping costs stop you.