>>9You will be fine doing this in most of the Pacific Northwest. I wouldn't do it down south, though. Things go badly far faster in warmer climates and southern places in the US tend to have a less "open" mindset when it comes to dumpster diving.
You know the basic rules:
Canned foods are great to go for
Dried meats are also good to go for
Avoid all fresh meat
Try to avoid starchy things that accumulate mold and bacteria quickly (bread, for example)
DO NOT dumpster dive out of public trashcans
ONLY dumpster dive out of commercial bins
You are best off dumpster diving out of commercial bins in the suburbs. These areas have few homeless people, the bins are usually not well secured, and there isn't really much competition.