Buy a plastic shoebox from your local dollar store. Wrap each brownie in plastic wrap and separate the layers of brownies with cardboard as pdswife instructed. Tape the lid on the box securely.
Put the box of brownies in another box with at least 4 inches of room all around. Fill with packing "peanuts" or popped corn. Send to me. Half Baked just told me she didn't want them.
We had sons in the military overseas that we sent baked goodies to all the time and they always arrived safely. Best of luck.