I've been reading (as have most) about the recall of tainted peanut butter products. I think bad advice is being given in an overly simplistic way - that is, advice to simply "throw away" the bad product.
Obviously, most of the producers of the bad product hope most consumers throw away any proof they may have. I suggest you keep the jar lids as a bare minimum. Keep the proof of purchase or the label. You're going to need it later, perhaps.