I worked a job where we cleaned up freeway medians and escapements.
You honestly would be surprised at how much loose cash is just on the side of the freeway. Split among four co-workers, in a three month period, we found over $600+ between us. We used to joke it was like getting "tips" for picking up trash.
Also, lots of stolen items get "ditched." I heard a story from a former co-worker that last year someone found an in-box Nintendo Switch, and they ended up bringing it to work every day to play on downtime.
The biggest win though, came years before I was in the program. A twenty-something kid found a gym bag with $10k in it. It was reported to authorities, but since no one was ever able to pinpoint who the owner of the money was, the guy was allowed to keep it. That's the part that surprised me the most, this is a State job, despite being seasonal, and I honestly expected the State to confiscate something that big, but nope, it ended up in the hands of the person who found it. What a payday! I was told this story by the old-timers.
Oh yeah, we also once found the aftermath an Amazon truck that had wrecked so bad the driver had died. We found that out by trying to dig up recent police reports on accidents in the area. The truck was gone but all the packages were still there... It certainly looked like Amazon had no intent to come clean it up, because this was a few days post-accident.