#4: Peppermint (Mentha x piperita).
Peppermint is a hardy and easy-to-grow perennial that will tolerate most conditions, but prefers moist soil (where it can get downright invasive). Drinking peppermint tea can fight or prevent headaches, indigestion, bloating, and gas. Cold tea applied to the skin soothes itchy, irritated skin, as does an herbal paste (poultice; see plantain entry for directions) made by grinding or chewing fresh leaves. To make mint tea, cover 2 teaspoons of minced fresh leaves or 1 teaspoon of dried leaves with 1 cup of boiling water, allow to steep for 10 minutes, strain, and enjoy. Tea can be also be frozen into ice cubes to rub on your skin for instant relief (they are tasty in iced tea, too, so make lots!) or stored in a spray bottle in the fridge and used to cool and freshen your hot face or any areas of irritated skin.
#5: Jewelweed a.k.a. "touch-me-not" (Impatiens capensis).
If you suffer from poison ivy/oak/sumac or have stinging nettles growing nearby, you need to know jewelweed! It is a fleshy-stemmed annual weed that grows up to five feet tall, and has blue-green leaves with small horn-of-plenty-shaped yellow or orange flowers. Later in the fall, those flowers are followed by plump seedpods that pop violently, throwing their seed contents many feet. A common wild plant throughout North America, look for it in moist areas, along creek banks, for instance, or in partial shade. For your herbal first-aid kit, you'll want to use the stems, which are fleshy and can be used like aloe leaves for the same skin woes. Use it fresh by slicing the stem open and smearing the jelly-like juice where it is needed. If you happen to touch poison ivy and can't get inside to wash off the rash-causing oils, look for some jewelweed right away and rub the juice over the exposed area to prevent a rash. It is also a fast way to put out the fire of a close encounter with stinging nettle.
To store the goodness for later use, you can make jewelweed tea and then freeze or refrigerate it. Cut the entire plant into 1-inch chunks, cover with water, bring to a boil, turn off the heat, cover the pot, and allow it to steep for 20 minutes before straining. Store in the fridge for up to a week, or freeze in cubes for longer storage. Jewelweed tea is also a good base for making a soothing lotion.