I could have used this several times! Clever and simple idea – and it fits a yard waste bag! Details from Lifehacker:
If you routinely camp, have outdoor picnics or throw parties you might find it useful to have a trash bag holder that can be stored away when not in use. Build your own with PVC pipe, joints, and wood or another material for the lid.
PVC project weblog PVC Plans shares a simple trash bag holder project. The exact dimensions will depend on what thickness of PVC pipe you use, but the basic structure will be the same—two squares that each have T-connectors for the two posts that hold up the top of the holder. You’ll then make a top out of any material heavy enough to not blow away in the wind such as plywood. Finally you can spray paint the entire setup if you like.
PVC Trashbag Holder | PVC Plans