This is a good time to check out medicinal plant field guides and get familiar with which herbs grow in your area. Wildflower guidebooks are good to help because many wildflowers have uses in herbal medicine. I also have links to many plant photos on my links page to help you get started. Some of our most common weeds have medicinal uses. Dandelion , for example, has a long-standing reputation in folk medicine as a liver and digestive tonic as well as many other uses.
Chickweed is a common yard weed commonly used in herbal weight loss products.
St. Johnswort is abundantly found in abandoned fields all over North America, and is one of the most popular herbs on the market now. There are many others. I have been able to prepare many herbal remedies for my own use from several very common plants, thereby eliminating the need to buy a lot of things I like to keep on hand. The very act of finding and harvesting these medicinal plants is good exercise in itself, therefore providing additional health benefits. Above all is the spiritual aspect of enjoying Nature, which is what makes this something I am drawn to do year after year.