With double digit inflation likely in the next 4 years, your money in the mattress will soon be worth less than the straw you took out to make room for the money.
The best depression era investment was farmland. I've spoken to dozens of depression era people, and those who had it best were those who could grow their own food. In terms of this side of eternity, "how can you have too much of something that lasts forever?" (I think that's either Pearl Buck or Scarlet O'Hara. :>)
Next comes guns and ammunition and stored food.
As a safe financial investment, you'll have to look at those who funded him: OPEC, trial lawyers, investment houses, hollywood.