Remove green tops from green onions; reserve for another use. Cut white portion of each onion into 1/2-inch pieces.
Melt butter in a medium skillet over medium heat. Add the onion pieces and pepper; cover and cook 3 minutes. Stir in peas and water; bring to a boil. Cover and cook 5 minutes or until peas are tender. Uncover and cook 2 minutes or until liquid evaporates. Remove from heat; stir in marjoram and salt.