All paper currency today is "fiat" money whose value is determined by law, not by something of substance that is promised in exchange.

However, people do collect paper currency, just as some fools collect obsolete casino tokens and chips [g].

By the way, there are casino tokens today whose intrinsic value in gold or silver is higher than the original value marked on the token. This includes some "silver premium tokens", and a few high-denomination slot tokens, ususally a $100 or $500. So you could say that some casino issues are closer to "real money" than the stuff the US Mint and the Bureau of Printing and Engraving produce.