I must live in an area ripe with people who always check the machines or people who know to check them when they are depositing. I find nothing. Always clean. Very nice find!!
I have picked up some rejected Canadian coins, but never any silver. It just surprises me that anyone would leave behind a rejected American coin. Wouldn't they still say "hey, this is still a quarter" and put it back in their pocket?
I used to find coins of varying quantity in the reject slots of CoinStars quite frequently but starting in around 2011 or so the finds dropped off to practically nothing. It turns out the CoinStar machines (at least out here) started playing a video of an animated hand reaching down into the slot and tells you to pick up the rejected coins as you put them into the machine! I started finding foreign coins and tokens being left on the counter with increased frequency around this time. Clearly, customers are picking up their rejected coins and sifting through what they want to keep or leave behind whereas before I'd usually find these kinds of things in the reject slot itself. Oh, and I still have that amazing find where the reject slot is packed full of coins but that is a rarity these days.
That's what happens here. They tend to take the US coinage but I do find foreign coins sitting on the machines sometimes.