Yup that would be shredded paper!! I asked Hunter what it was all for and he informed me that they were for his friends because they were having a paper party. Duh!
I now have a nice little shredded paper trail from the shredder to the playroom. I set them to start vacuuming the little trail up and then I hear, "I can't vacuum all of that up!" I go to investigate and one of the containers was dumped out by Jacob. Lovely.