This is actually considered a lost art, due to the adcancements in chemistry and food safety labs, but identifying edible plants is a good skill to learn:

If at any point irritation occurs such as rash, dizziness, stomache cramps, or drowziness occurs, stop immediately. Do not attempt while preggers. I am not a medical doctor and this is not health advice.

1. Collect several samples of unknown plant, make note of color, stalk, leaf, fruit/flower, and root characteristics. Preferably start with plants local fuana are seen eating.

2. Dry some of the plant.

3. Try boiling a very small portion of the plant.

4. Apply results to small patch of skin. Record results.

5. Hold some of water in mouth for a few minutes then spit. Record results.

6. Nibble on small amount of boiled plant. Record results.

7. at slightly larger amount of boiled plant. Record results.

8. At this stage, some plants might grillable or burnable for incense. Record results.

9. If all previous tests pass, attempt to nibble raw plant. Record results.

Do not expect to identify more than a plant or two per week, do not expect the same plant to be safe at every growth stage, environment, or season, and remember most useful plants were identified as safe to eat in the last several hundred years and that picking up a book could save you the trouble. In a survival situation, it is better to rely on rodents and fish for protein and calories, there is a reason our ancestors were ambush predators.