Somebody finds a chest of money and starts planning how to spend it. It turns out that it's Confederate and worthless.
Nowadays, if you find a trove of CSA bucks you could make out pretty well if you know how to market it to collectors and enthusiasts.
Watch out for cheap replicas (I have some of those from when I was a kid).
When you stop and think about it how would anyone know the difference between issued and replica? ;’)