Here in zone 5, my medicinal herb gardens (I tend to naturalize the stuff all over the farm- it saves weeding, and can save a population if some part gets diseased or the cows find it!) contain the following:
skullcap (scutellaria lateriflora). THE best "nervine" and calmative I've found.
Lemon Balm- also a mild tranquilizer, but is effective against some viruses, as well. I make lip balms with it for cold sores.
Black Peppermint- powerful mint which is good for digestion, can help clear your sinuses, and is good for flavoring herb teas which have other, less tasty herbs.
Catnip... mostly a beverage tea, but seems to helps colds and flu.
Garlic- the most potent antibiotic you can grow.
Lovage- mostly culinary, but is a warming digestive as well.
Calendula- the petals are a powerful antiseptic and anti infective. I grow a bunch of them for use in a soak I use for infections.
Chamomile-excellent beverage tea. Good for digestion and can help calm someone and help them sleep.
Dandelion- early spring salad herb, the root is an excellent blood cleanser, diruetic and liver stimulant.
Black Cohosh- woman's herb, especially for menopause.
Dill- the seeds work great for nausea and gas.
Echinacea- both roots and above ground parts help boost the immune system
Elecampane- excellent decongestant, helps when lungs are congested.
Feverfew- headache remedy, especially for migraines
Hyssop- for a soothing tea.
Joe Pye weed- old remedy for many infectious diseases.
Lavender- nervine. Also the essential oil is strongly anti bacterial. It's also valuable for covering odors, like in a sick room.
Marshmallow- very soothing, excellent for gastritis and also bladder irritations.
Nettle- High in iron and vitamin C. Excellent nutritious food. Some people swear by it for arthritis.
Oats- a tincture of the green oats is helpful for some "mens" problems.
Pennyroyal- I grow it for bug repellent.
St. Johnswort- a valuable anti-depressive. But the oil (made from the flowering tops, soaked in a good oil) is valuable for treating burns and skin conditions.
Thyme and/or oregano- both are powerful antibiotics, the essential oils especially.
Valerian- a tranquilizer and nervine, although I prefer skullcap.
Yarrow- dried flowers and tops, crushed, will stop almost any bleeding. It's also strongly antiseptic.
I also harvest wild black cherry bark for coughs. Coltsfoot is also useful for coughs, but has the same problems with possibly causing a rare, fatal liver disease as comfrey. Use it VERY sparingly, and with care.
Comfrey is valuable, but is not recommended for internal use.
Horseradish, as well as being a great culinary item, can be used topically to increase circulation and treat aches and pains.
Wild sweet violets are edible- and tasty. But I also make a tincture from them and add it to my homemade cough syrup. They are very soothing.
Shepherds Purse is a strong styptic or bleeding control. A tincture made from the fresh plant is much more powerful than using the dry plant.
Lobelia inflata is anti spasmodic, but is also very powerful. Use CAREFULLY if you must.
Yellow dock is another liver tonic, blood purifier, bitter herb
Hawthorne is an excellent heart herb. Fairly safe and mild (compare to Foxglove, for one example) it can help regulate irregular heartbeats, and help relieve congestive heart failure.
A couple I can't grow- saw palmetto. I keep dried berries on hand. It's probably the best herb for prostate problems that there is.
Milk thistle seed- powerful liver protectant and even can help the liver restore and heal after serious problems.
Licorice root- THE best solution for severe gastritis, acid reflux, etc. It will heal stomach ulcers, often faster than Rx stuff. You need to be careful about how much you use, as it can affect the adrenals and cause some people to retain water and possibly raise their blood pressure.
Rose hips- excellent wild vitamin C source, add it to teas for colds and flu.
Elderberry- valuable herb for influenza.
Raspberry- leaves are excellent for pregnant women and for during labor.
Blackberry leaves can help stop diarrhea.
There are many others. You'll find as you get educated and experiment, that you develop favorites which work especially well for you and your family. Don't assume that "natural" means "safe"- not always true. And remember that ANYONE can develop an allergy to anything, and be alert for signs of problems. It's best to not start a treatment regieme (unless you are very experienced) even on yourself by starting several different herbs at once. If you have some adverse reactions, or you start feeling worse, it's difficult to track down exactly what- or what interactions- is causing it. The safest way to use medicinal herbs if you aren't very well educated about them is the old "simples" method. Use one herb at a time, by itself and give it a chance before adding more.
Just the time I spend working in my gardens; planting, weeding, harvesting... is therapeutic.
Summerthyme