The Zombie Pillow is a pillow that is unobtainable in the store/pillows page in PFS. The only way to get it was to buy it during the Halloween Event 2017. The pillow design is of a Zombie, which is the same for the particles.
So, how else do you sell more gory pillows to kids on Halloween? Give them to NREF and brand it as "educational" (we can't use the full name due to the restrictions they embargo on us).
Still, pretty gruesome way to sleep, correct?