Agricultural crops have been bred for many years for taste, color, pest resistance, uniformity, and – most significantly – high yield. The nutrition levels are rarely selected for. On the other hand, plants growing in nature have motivation to accumulate as many nutrients as possible (and they still taste good too!). Any minerals they do not use leach down in water seeping deep into the ground away from the topsoil that plants can access, harming the entire ecosystem by decreasing the amount of nutrients available. All organisms want nutrients to remain in the system, and so they are constantly recycled between animals, fungi, and plants. This is how an ecosystem maintains its health, and causes wild foods to have higher nutrient levels than cultivated crops.
Many wild edibles are perennials, which have been proved to be richer in minerals, vitamins, and protein. This makes sense because the plants have more developed roots and more time to accumulate nutrients. Below are some charts, from Martin Crawford’s book How to Grow Perennial Vegetables, that compare annual and perennial (some wild) plants:
In addition to the plants’ adaptations, the soil in natural ecosystems generally has better fertility than in agricultural soils. Most human managed fields have been plowed, over planted, and chemically fertilized. These practices lead to degraded soil, whereas natural ecosystems have intricate webs that work to build fertility and hold on to the maximum amount of nutrients.
Foraging allows you to eat extremely seasonally which feels healthier and seems to be what nature intends us to do. Nature has a reason behind growing what it does at certain times of the year. In the winter, when it is too cold for above ground growth, perennial plants store their energy in bulbs or tubers. These are high in starches and carbohydrates and make up the majority of food nature provides during this season. Then in the spring, everything changes. Spring ephemerals, the first plants to sprout in the spring, are especially high in nutrients because these plants rush to accumulate nutrients that would otherwise leach down into the soil with the melting snow. These plants are also generally detoxifying, which is beneficial for your body after eating a carbohydrate based diet all winter.