How do you make paper / papier mache?
Actually the first person to answer was right before she corrected herself. PVA glue and newspaper will make a very strong structure. For a scarecrow head use a large blown up balloon and cover it with layers of newspaper soaked in PVA glue. Do a maximum of two layers at a time and then let them totally dry before applying more layers. The layers take a long time to dry thoroughly and to get enough layers to make a sturdy head will take a couple of weeks. If you’re making an entire Humpty Dumpty you could use a beach ball I suppose. You’d need loads of PVA glue though. Good luck in the competition.