The Diversity of Food

There are many different plants that humans can consume other than the three main crops. We use oats, barley soybeans, and flaxseed in our foods but not as a major part of our meals. We can also eat wild plants for instance cattails are an edible plant. When selecting young cattails you need to watch out for their look-alike the Irish shoots. Humans could also eat the plant watercress which we already use as an ingredient in V8 cocktail juice. It can be found throughout the United States. Water cress is high in vitamins C and A. Kelp is also a plant that humans may not eat regularly. It also is edible and the salt it contains prevents muscle cramps.
A few people produce food for big numbers of people. If those few people only have the skills, technology and infrastructure to produce three main crops then we are at risk should something go wrong with those people or those few crops. We run a risk of infestation of a pest causing a mass destruction to our crops or to our storage.When planting only a few crops over and over it depletes the soil. You will often see farmers plant legumes after they harvest their main crop to regain the nitrogen.
A positive aspect on society of the result of our main crops we rely on being annuals is that we can be sure to plant and store accordingly. If we need more of one crop we have the chance to plant more of the crop we lack of in our storage. As long as we can preserve our storage of these crops we can survive. The down side to that is we have all our "eggs in one basket". If we drop the basket then we destroy our crops.