I've found 10's and 5's a few times over the years. I saw a lady once go through the change returns of all the payphones in a central bus station looking for coins. I've heard that returning shopping carts for the quarters in grocery store parking lots can be ok money at some times of the day too. Airport carts here use $1 coins but I think they look out for people trying to make money that way.
I swear on everything holy that I once found a $100 bill in a parking lot.
Picking up all coins you see on the ground- fine. Going out specifically to look for coins on ground- hmmm. (metal detecting ok.) Masses of people roaming streets looking for coins on ground- bad.
JMO wags
Only when they CAN'T have it, ......THEN they'll want it.
I love Cents. If you get an UNC box, you win. If you get a regular circ. box, you win. If you get a zinc box, you don't lose....so you still win.