Canned meat remains a mainstay for long term storage. Things get rough and that can of Spam you turned you nose up at might start looking good.
I have eaten fire rations (at the time C rations; now fire rats are MREs) with relish and gusto several times while on a fire line. Circumstances really do affect the decision about what tastes good.
What is interesting about the development of emergency rations (MREs) today is how good the present stuff is, even consumed in non-emergency situations.