Learn about the plants in your area. I live in Northern California and every spring you see acres of yellow flowers. Most people ignore them, but a few know that you are looking at wild mustard. They are good to eat and you can make mustard from them.
Some people eat the flowering tops just before they open. They are cooked like broccoli. My wife was raised eating the leaves. The tender young leaves are used for cooked greens or in salads.
To Cook, wash the greens well and cook in salted water. Wild mustard can be somewhat sharp when raw and somewhat bitter when cooked. Blanching it or boiling it in water for a few minutes will remove the bitterness (the longer you boil the less bitter it’ll be). It can be used like spinach in any recipe.
Chickens and the rabbits love the dried stalks as a treat in the spring and summer.
Wild Mustard grows in most of the U.S. You will see it in the spring to early summer.
Mustard plants are most easily identified by their small and plentiful yellow flowers, growing in clusters atop a long stem. If you look carefully at this picture, you’ll see that each of the flowers has four small yellow petals, and they’re in a cluster
If you have any doubts as to the identity of the plants I recommend you review the video at the following link
A good rule in foraging for wild plants is to always find a local expert to learn from, there are lots of poisonous plants out there.