Depends on what it looks like and if it has any meaning or remberance value. If it's a plain little white paper box, it's going in the trash. :)
If its cardboard, it gets recycled. Or used to start a fire.
In the cardboard recycling bag.
I would keep it. I have a collection of boxes, all sizes, they come in handy at Christmas.
Save some, toss some
Throw it away, i already have enough for...in case.
Throw it away.