But I do like the Two-Face idea, although Two-Face is usually depicted as using a silver dollar as his coin of choice, which are made of... well, silver.
Don't be so sure...I haven't look into the specifics of the composition of every silver dollar
Most use .77 troy ounces of silver.
nor the specific silver dollar Two-Face might have carried (besides it having two obverse sides)...
In the most recent incarnation of The Dark Knight, he uses a 1946 Liberty Dollar, improperly struck with with two faces (making it a worthwhile collectors item regardless), which is made from... .77 troy ounces of silver.
but it's very common for coins not to have much, if any of a metal they were designed for in order to save cost. Gold and silver coins? Yeah...lots of them are actually gold or silver colored. They may or not not even have a gold/silver plating. They may just look like it and almost certainly aren't made of the metal anytime in the last hundred years. It's just too expensive in the last century. Silver and gold cost far too much to make a coin worth only one dollar.
The first silver dollar coins, the Continental Dollar, were minted from silver. The 1804 silver dollars (oddly minted in 1834) are rare enough to be irrelevant and certainly worth more than a dollar, were 90% silver and 10% copper, making them closer to sterling silver. The seated liberty dollar was minted from 1840 - 1873 and used this same ratio of metals, as did the Trade Dollar, Morgan Dollar, and Peace Dollar. The Eisenhower and Susan B. Anthony dollar coins, the most recently minted dollar coins to have a silvery color, were 75% copper / 25% nickel and 91.6% copper / 8.3% nickel respectively, and are generally regarded simply as 'dollar coins' rather than 'silver dollars', like the later Sacagawea and Presidential dollars.
My parents used to collect coins. I pick stuff up.