This elderly man we visit gave us some VERY OLD crackers. They were a few years past the "best by" date, but there were no obvious bugs in them. Yes, they were VERY stale, but otherwise they were all right. We lined them up on the dehydrator trays and dehydrated them for a few hours ... nearly as good as new! They still had a slight 'stale aftertaste', however they were very crisp again.
Another thing I discovered recently ... the other day I was making buttered noodles as part of our dinner. I had just finished off the last of the pretzels (there were only a few of them!) and the empty sack was sitting on the counter. Buttered noodles need salt, and there was the empty pretzel bag right in front of me with all that 'rock' salt at the bottom of the bag ... about to be thrown out!! I added some of that salt, and then saved the rest in a small jar; there was about 2T in all. Now whenever we are done with pretzels, we will save the salt and use it for soups or whatever.