This is not just for grains, flour, sugar and such, but also cleaning products, paper goods and anything that I can freeze. This is where having a nice Price Book comes into play. A bulk purchase is a waste if the price per pound is not a savings. Don't assume that just because the package is large that the savings is there! Because of my price book, I know what the "normal" prices are and what the "sale" prices will be (within reason). Also, something to consider, if the product that you are buying in bulk can not be used before it goes bad, IT IS NOT A SAVINGS!
Food thrown in the trash is no different than throwing money in the trash.