'Tis the season for corny sentiments, so do like the Woodard girls of Alvarado, Texas, and tell your teacher (or a friend) she's tops with a card that doubles as a snack.
Cut a popcorn-box shape (ours is 8 inches tall and 6 inches across at the top; or try our template) and a smaller rectangle for a label from the card stock.
With a ruler and marker, draw lines on the front of the box. Add a message and a border to the label, then glue it in place.

Tape the popcorn to the back so that it sticks up above the container.
Suggested messages:
To a pop!-pop!-pop!-ular teacher
I don't mean to be corny, but you're the greatest!
I'm e-kernel-ly yours