I call it scavenging. I've got lots of stuff scavenged...books, furniture, some clothing. I've never scavenged for food to eat; however, I have been known to pick up dry
and not leaking
bags of veggiescraps from outside groceries to take to the local community garden to add to their compost.
I also run my car on veggie oil...used when I can get it.
You want disgusting? You ought to see the condition of the waste oil containers at many restaurants. Using a oil suction pump nozzle carefully enough to avoid the floating rats, etc. is a special skill.
One place I lived had a whole-evening, neighborhood social event around Big Garbage Night. People would put out what they didn't need, walk around and look at what others were getting rid of, comment on it, and frequently take something home. All ages, all classes. Some people would go to other neighborhoods for different kinds/quality of things. I got a really interesting pair of legs/supports for a glass or wood table top (coffee table height). They were made out of iron and looked something like rustic andirons. I guess the top had broken. And then there was the antique sewing machine legs/treadle that I topped with a piece of marble that had also
come off the street that had some stains and was really worn. A little lemon juice and super fine steel wool took care of that.