Food found in crashed ships and old bunkers can sustain you for so long. Sooner or later you have to start growing, and for that you need seeds.
The complete guide to growing food in Planet Crafter – Planet Crafter Guide
Farming in The Planet Crafter requires seeds. They can be quite hard to come by on a habitable planet, but there should be enough to meet your needs. That is if you know where to look for them.
The only way to get seeds is to loot specific storage boxes and abandoned ones. The contents of these seem to be somewhat randomized in each game, but the general area of finding seeds remains the same.
Now, since the items in the containers are finite in The Planet Crafter, you may be afraid that you will run out of seeds at some point. But that's not possible – after placing a seed in the food grower and harvesting the food, the structure will also return the seed you've used. So every seed you won can be used endlessly to grow more crops.