What is the highest value coin that works in a vending machine?

Some vending machines (parking lot or public transportation/subway) give back change in US Sacajawea dollar coins. That’s about the only place I have seen them recently.

I can’t think of a vending machine (drink, candy, etc.) that takes anything but a quarter.

Most US Vending machines have been equipped with credit card readers; most people don’t carry cash at all.

In my neck of the woods, as far as “coins” go, they take nickles, dimes, & quarters…NO pennies. Many of the newer ones take crisp dollar bills as well. A few will take 5’s & even a fewer take 20’s. I’ve heard a few are now taking debit cards, but I don’t use them often enough to even know for sure.