There are a number of reasons you might want to use wild plants as food.
Wild plants have some unique flavors that can be among your enjoyed favorites. Watercress with something sweet such as pancake syrup in a peanut butter sandwich is one I particularly enjoy. Dandelion greens pesto mixed with sphagetti sauce is another.
Since taste of many wild edible plants is so different from usual cultivated vegetables, you likely will at first not accept some of them as a delicious flavorful food. Just about any food flavor other than sweet, saltly, starchy, and fat are, I suppose, acquired taste. It takes time for your mind to recognize an unfamiliar flavor as a 'tried and true' favorite. Introduce a wild food into your diet by eating a small amount when you are most hungery. Repeatedly doing so can make new food one that you especially enjoy.
The amount of vitamins, minerals and other nutrients in wild food, according to many sources, is on average, greater in wild foods. Domesticated vegetables have been selectively bred for looks, production quantity, taste, length of storage and other qualities other than nutrition.
The fruits and vegetables sold in supermarket have been chemically fertilized; exposed to herbicides, pesticides, fungicides, and a variety of other chemicals; and they may have been genetically modified and/or irradiated. The safety of eating such produce is of concern to many people. Wild foods for most part, avoid those concerns. If you do gather wild foods avoid taking them from along roadsides, lawns that have been treated with chemicals or any other areas that may have been treated.
There is possibility that supermarket food can be contaminated with pathogens. Dozens of diseases can be spread by an infected person handling food anywhere from time it is harvested until it is put into your grocery bag. Plants growing in wild are untouched by human hands.
Wild plants can be prepared in many ways. Greens can be put through a food processor or blender to make pesto. Add just enough oil and/or water to let mixure process well. The pesto can then be easily mixed with other ingredients such as peanut butter, tomato sauce, or syrup for flavoring.
Some greens such as lambsquarters, chickweed and purslane can be used anyway spinach is prepared. Strong or bitter tasting greens can be boiled changing water once or twice to reduce bitterness. This is sometimes done with dandelion leaves. Then other ingredients can be added for flavoring and texture.
Wild fruit can simply be mixed with nuts or seeds such as sunflower seeds or almonds.