Towards the end of the American Civil War, the Confederate States' dollar became nearly worthless due to massive inflation (similar to the phrase "not worth a Continental", stemming from the Revolutionary War, or the more recent hyperinflation in Zimbabwe).
A simple explanation (thanks Alicja Z) is that it's this inflation that she was referring to.
Another possibility: Being so worthless, you could almost say that the money had become fake. She could also be implying that the fakes are worthless, or not as valuable, as the real thing. If Roger's comment is correct and she said "counterfeit", this meaning of "fake" becomes more directly true.
Silicon Valley wasn't part of the Confederate States: Texas is as far west as the states of the nation had gone by that time. So it's very unlikely that this is the intended meaning.