Food is food. By more of what you already eat. If you want to really cover you butt, buy some filler in bulk. 40 lb. bags of rice are relatively cheap.
Make sure you have several firearms and plenty of ammunition. Silver is an iffy proposition. Supposing a real SHTF situation, I don’t care much about precious metals.
Laterday saints are stocking 2 yrs food....good instructions there..http://lds.about.com/od/preparednessfoodstorage/p/foodstorage.htm.
Silver is historically 15 to 1 with gold so it should be at 114.98 today..if it were following historical trends...