Sort peas for stones and debree and wash. Place in a large Dutch oven and cover with two inches of water. Soak eight hours; drain. Return peas to Dutch oven. Add onions, bell pepper, celery, green onions, garlic, ham, ham bone, salt, basil, thyme, marjoram, mace, and bay leaves. Add water to cover by one inch; stir well. Bring to a full boil over medium-high heat; reduce heat to low. Taste; adjust seasoning with pepper and cayenne.

Simmer gently for one and a half hours, stirring often and adding water as necessary. Taste; adjust seasoning. Simmer an additional 30 minutes or until peas are tender and liquid has thickened. Serve warm over hot cooked rice. Garnish with parsley, if desired.