I just wanted to mention this if you need larger boxes.    Home Depot has moving boxes and they are cheap compared to most places.  They are great for pillows and blankets.  I wouldn't send anything that weighs a lot even though the test weight is decent.  They are made from recycled material and don't seem quite as sturdy as others.

There are three sizes that I saw.  The small  is 1.5 cu feet and is 67 cents each.
                                                 The medium is  97 cents, sorry I don't have the measurements.
                                                 The large is $1.97, I don't have the measurements on this one either, but it is BIG!

I believe you can get the sizes on their web site.