Packing Boxes For Moving

When I was a child my mother dumpster diving behind the pharmacy for moving boxes. I'm not sure what the law is that, although in Maine. It seems unnecessary and expensive to buy U-Haul. So, any suggestions?

groceries
get boxes from Apple

You may be able to get them from supermarkets or other shops, especially if you catch them when low, so they can open the box by removing the shutters rather than using a knife to remove the box top of the box.
The main problem is that (and with the idea of dumpster diving) is that the boxes may have bugs in them, where you can not see them (as in parts), then you will bring to your new bug home.
Check Craigslist, maybe someone just wants to move and get rid of their boxes for free or at a lower price than you would pay the U-Haul.
Another option is an office - the boxes copy paper printer / future are good for packing. Many people where I work use for storage and travel.