All office supply stores sell packing materials including boxes. But if you are looking to save money, you can use a website such as www.usbox.com and order them.
I think the best place is wholesale bazaars and markets that sell packing boxes for different goals and different goods. Manufactories can buy those packages and fill them by their goods.
You can often find boxes at the liquor stores
Check out BoxGiver. People give away their moving boxes for free on there
Most professional moving companies and some chain stores sell very high quality boxes. When purchasing boxes make sure they are thick (three ply is recommended) and that none of the boxes are damaged.
If you are looking for moving boxes shipping stores such as FedEx and UPS sell boxes for people that are moving. Other office supply stores sell packing tape and labels if you need those things as well.
If you have a U-HAUL near you, they should sell packing peanuts. Sometimes a FedEx or UPS store might sell packing peanuts.
There are many stores that one can get packing paper at. Some stores that sell that are Walmart and Target, They both have a wide selection to choose from.
mad 4 boxes is a company that sells a wide range of packaging supplies for many different purposes, such as moving house and putting things in storage. they also sell a wide range of bubble wraps, packing tissue and foam wrap, to protect your breakable items.
The stores that sell jewellery boxes are Sears, Target and Walmart. There are more other stores that sell jewellery boxes in different places and in online too.
You will find tons of nesting boxes at B&Q. I think they don't sell type of boxes these But I'm not really sure if they sell nesting boxes only for chicken.
Post an ad on Craigslist for your city in Rhode Island and advertise you have new cardboard boxes to sell.