Otherwise known as: how much can YOU fit into a Priority Mail Flat-Rate box?
That is one STUFFED box. There are 2 15-packs of Extra gum, an entire bag of fun-size Snickers Peanut Butter Squared, and nearly an entire bag of fun-size standard Snickers. Only 3 candy bars wouldn't fit in the box. I'll consider those my tip.
It would probably be cheaper for me to just drive over and drop off a bag of treats, but there's nothing like getting a package in the mail.
Happy Halloween, Big Brother!