On a completely different thought they could make musical instruments out of recycled containers and materials. EX. Put buttons in to two cups and tape together to make a shaker. Your pillow idea seems good, but could involve quite a bit of work. I think that you have to stuff them with recycled materials, though. Also make sure that they bring in a small t-shirt, even something from when they were a baby. Maybe you could have a sewing party and some extra adults could come into assist during the stuffing/sewing stage.
How about a toy exchange, or making puppets out of stuffed animals. Just some crazy thoughts. Kids will remember these activities forever and active learning is so right. Have fun!!