I had some pantry overflow in the laundry room, back before I was even a prepper, and some stuff on back shelves got pushed back, covered and forgotten. My DD brought found it today, and I tested it.
I ate a rice krispy treat that expired in 2004, it was excellent, tasted brand new and it was over twice as big as the ones I bought last week!
I ate some cereal that expired in 2003, it was stale and a little, tiny bit rancid tasting but edible. (Generic cinnamon toast crunch)
DH ate some peanuts that expired in 2007, they were perfect. (They were in a can.)
We used taco seasoning that expired in 2003 to make tacos, and shells that expired in 2004 (stand and stuff, they quit making those when they started making the shells so thin they break as you stuff them!) The shells were extremely stale, but heating them in the oven made them crisp and yummy again. No bad taste that anyone noticed.
I was very disappointed in the pop tarts. They expired in 2003 and the hot fudge sundae kind looked a little discolored in the middle, as thought the filling leaked through, we didn't eat those. The strawberry ones were very very hard and dry, but edible. Not pleasant, but edible.
The Banquet Homestyle Bakes Complete meal kits looked fine, as did the Betty Crocker Complete meal kits (the kind with dried pasta and a can of meat filling, like hamburger helper with meat.) The Slow Cooker Helpers looked fine, and I've already eaten 10 year expired Hamburger Helper and cake mixes, so I'm pretty sure those were still OK.
There were other cereals and cookie and brownie mixes we still have to try (discontinued cereals, I wonder if they'd sell on Ebay? LOL) including Honey Graham Life cereal, I don't expect much of it since I know graham doesn't hold up well, but the peanuts surprised me so maybe it will too.
I hope we have some Oreo cereal in the basement somewhere, I miss that stuff! It was discontinued for not being nutritious enough. Dang cereal company! Who cares about that?
Most of my storage is in the basement proper, and it stays cool and dry. The laundry room is hot and humid, so this food wasn't kept under ideal conditions.
Overall, I was happy and relieved.

lmao
good post