He learned how from his slaves.
Peanuts are a strange plant.
They're not really a nut but a bean. They grow on a vine like a green bean, the only difference is that the peanut grows underground. What happens is the flower that grows on the vine buries itself in the dirt and that is where the peanut is formed. Peanuts originated in South America, then went to Africa, then came to North America. George Washington Carver led a remarkable life.