Our USAR team at work apparently stocks enough emergency rations to feed the whole company for a couple days. It's in the form of foil wrapped cookie things that are kind of like shortbreads. Several years ago someone who is on the team offered me some that were 5 years post expiration. They have a nominal 5 year shelf life, so 10 years old at that point, figuring (correctly) that I wouldn't have a problem trying them, and if they weren't stale or nasty would snack on them. They were fine. So much so that I ordered some for my own earthquake kit.

Lots of dried herbs and spices are usable well past their expiration dates. Mostly they just lose flavor over time.

A colleague visits a research station in the arctic that has 40+ year old cans of Spam that everybody assumes are fine, at least to the extent that Spam is ever fine.

Flour can last a long time (years) if you keep it dry.

Honey will crystallize, but last millennia. All you have to do is gently heat it in a water bath and it will turn back to honey.

My mom had a single jar of mayonnaise in the fridge my whole life. The same jar. None of us use mayo, and we were all afraid of it, so it just lurked there. We always assumed it was bad, but except for one of my sisters we all assume that all mayo is bad.

Cornstarch should good indefinitely if you keep it dry and free of bugs.