Place green beans and carrots in 1 inch of boiling water. Cover, and cook until tender but still firm. Drain.
Melt butter in a large skillet over medium heat. Saute onions and mushrooms until almost tender. Reduce heat, cover, and simmer 3 minutes. Stir in green beans, carrots, salt, seasoned salt, garlic salt, and white pepper. Cover, and cook for 5 minutes over medium heat.