Eugene, a city in Oregon, generates less waste than many other American cities on account of a number of highly active environmental groups, as well as a general local consciousness which tends to opt for recycling or resale as opposed to disposal. Nevertheless, there are many pockets of very profitable dumpsters.
A good source for bread is behind the Metropol bakery on S. Willamette. The bread is usually in bags, or in a large pile, not touching the dumpster walls.
There is also the dumpster behind Humble Bagel on 24th and Hilyard where there is usually an abundance of bagels in paper and plastic bags. Adjacent to Humble Bagel is Sundance Natural Foods where there is often some very delicious produce in the compost bins behind the store. Eugene is part of the Freecycle community, too, but instead of freecycle.com they have created their own yahoo group called Lane County Pay it Forward. It works exactly the same way.
Additionally, Each year at the beginning of June is what's known as "Hippy Christmas" when all the U of O students are getting ready to move out of the dorms and throw away heaps and heaps of usable items. So many things that the university rents extra dumpsters just for that time of year.