The list is extensive, but below are some of the better-known varieties.
The Legume Family is one of the most widely used Green Manures. Consisting of many different types of Clover, Peas, Vetch, and others, legumes contain symbiotic bacteria in their root systems, which help to fix nitrogen into the soil in a form that future plants can use.
You may have heard of using legumes in 'succession planting' - an idea that illustrates green manures in action. Because 'heavy feeder' crops like corn require nitrogen-rich soil to produce great-tasting ears, farmers and gardeners alike must figure out how to replace all of that nitrogen after each crop has been harvested. One simple answer is to plant beans or peas directly after corn - two well-known legumes that are infamous for leaving a slew of nitrogen in their wake. So, peas follow corn, which then gets planted again and is followed by peas (or clover, or beans), which then follow corn all over again - all in succession!
Other common green manures not in the Legume Family, including Rye, with its deep roots and hearty characteristics, great at withstanding colder temperatures and decreasing erosion, as well as buckwheat and sorghum.