Seven director David Fincher shares what was actually in the box, though he says "you don't need to see what's in the box if you have Morgan Freeman"
In the dramatic scene, Brad Pitt's Mills demands to know what's in a box delivered to him on the orders of Kevin Spacey's murderous John Doe, which Morgan Freeman's Somerset opens. Inside is the severed head of Gwyneth Paltrow's Tracy – we never see it, but it's obvious that this is the grisly discovery made by Somerset.