Commemorative silver dollars, that naturally cost a great deal more than a dollar each. They are actually produced by the US mint and are considered legal tender, but are only made in limited quantity and aren't in general circulation. If you really wanted to, you could use one of these coins (that costs $80 each) at its face value of $1 to pay for something, but I don't think that would be very economical.
Kor
Kor