that weren't from my business, the next time I found boxes in there I took them out and found address labels on them from a house across town. I moved the stuff to my pickup and took it over to the address and threw it on their lawn. When the person came out upset and asking what I was doing, I reported I was returning their trash to them because somehow it got misplaced in my dumpster, and bid them a good day.
They didn't argue with me and it hasn't happened since.