Others have mentioned Azure Standard as a source for bulk grains, as well as a variety of other goods, and I second their favorable endorsements. Those living in or near agricultural areas may find they can connect with grain farmers in their area and purchase grains in very large quantities directly. These purchasers may need to provide their own containers, but it’s common to have to repackage bulk grains from other sources for long term storage anyway.
Local growers may also have “feed grade” grains, so called because they have some amount of weed seed and other material in them and are therefore used as animal feed rather than sold for human use. These are much cheaper than the cleaner varieties, but are typically quite safe and, when ground into flour for instance, no less palatable than the more expensive stuff. Thanks. – RM
HJL Adds: I would be very careful about “feed grade” grains. My own personal experience with them was with a couple of 50lb bags of corn. We purchased them because no local company had whole corn. Within 2 weeks of purchasing, my house was overrun with small bugs. It took us a bit to trace the bugs back to the bags of grain, and we ended up losing nearly 300 lbs of various grains that we had not yet processed for storage. “Feed grade” grains are usually not treated very carefully in storage, and you may end up in the same boat we did.