What is the name of a rectangular piece of popcorn paper?

A piece of popcorn is called hollow popcorn.

It belongs to a kind of popcorn. A puffed food made of corn, ghee and sugar is put into a popcorn machine and tastes sweet. Put a proper amount of corn into the popcorn pot, seal the top cover, and then put the popcorn pot on the stove and keep rotating to make it heated evenly, and then pop the popcorn.