A. Shoots - most are eaten raw or cooked and served like asparagus. B. Plants - eaten raw as salad greens. C. Roots and tubers - cooked and eaten a potato substitutes. D. Flowers - large ones can be battered and fried, small ones eaten raw. E. Seeds - eaten as is, roasted or ground into flour.
Some plants involve more preparation than others.
Try to use plants that only need minor preparation for your own convenience. Before taking your students on a gathering walk, show them pictures and drawings of the plants they want to collect, and tell then the names of the plants. Caution them NOT to eat anything until returning to class. Many plants look similar and they do not want to eat anything they are not sure about. Go on a gathering walk and enjoy the outdoors.