I have a $10.00 example. The guy, whose name is Bernard von NotHaus, was charged with forgery/counterfeiting money. He went to trial and was convicted of counterfeiting in 2011. He advocated an alternative form of currency using his copper, silver, and gold rounds.He also printed paper money. His biggest problem was that the coins/rounds he made were much too similar to existing American coins. The paper was quite different than U.S. currency. For more reading or info just google Bernard von NotHaus Liberty Dollars.
It's kind of a funny story about how I got the one I have. Do you want to hear it? You do? OK, I'll tell it. I was working as a cashier in a retail store. On my day off, a customer came in with a $10.00 Liberty Dollar and asked if they could spend it in our store. The cashier on duty had never seen one and knew nothing about them. She called a manager who also had never seen one and knew nothing about them, however the coin had certain things on it(and these are what got NotHaus in trouble) such as Lady Liberty holding a torch, the phrase "Trust in God", and other details similar to real U.S. coins. The manager, not knowing better, assumed it was real and allowed the customer to use it for their purchase, and receive the leftover difference in change. The next morning, when the actual store manager found out about this, he was quite upset. He knew it wasn't U.S. money, though he didn't know what it actually was. When I came in that day, I was told about the "major" blunder the previous manager had made, and how the store manager was very concerned about having to explain having accepted this counterfeit coin as tender, to his upper level bosses. I took one look at the coin and instantly recognized that it was a Troy ounce of silver. I didn't know the exact silver melt at that time, but I knew it was more than $10.00, so I offered to buy the coin for the $10.00 the store had in it, that way the manager was covered with his monies. I took the coin home and found that the silver melt that day was about $32.00 and that such coins were selling on eBay for about $64.00. The rounds are legal to buy and sell as rounds, just don't treat them as money. They're available on Ebay, usually at a premium over silver melt, and as usual with any coin or collectible, condition is very important. That's my story and I'm sticking' to it.
This is what the originals used. I was able to locate some news story's about city's and county's across the US that were using them in commerce. They were downloads but can't find them to upload. NGC https://www.ngccoin.com/boards/blogs/entry/50-original-1998-liberty-dollar-aka-norfed-dollar/ Photos of these have been completely wiped from the web, found some trump dollars, but none of the older coins.
You can see the similarities to U.S. Coins. That is what the gov was uptight about. NotHaus's paper money didn't look anything like U.S. paper money which is why Gov didn't care.