When the SHTF you will be on your own. Gathering food and hunting animals can sustain you but down the road society will need to be rebuilt. A key ingredient in rebuilding a society will be and always has been agriculture. Growing your own food initially will ensure that you have seeds available forever. Once you lose your seed that plant could be lost from you and your future village forever.
Modern plants that supply you with food today are all grown in high volume, high intensity, high fertilizer and pesticide use environments. Some of these plants require it. Those crops will not be ones that you will need to concentrate on.
Below is a growing list of crops that are relatively easy to grow, relatively pest resistant and fit the bill for a crop that can be propagated indefinitely.