In a pot, cook rice. (For more flavorful rice, add a chicken bouillon cube to boiling water.) Wash chicken and pat dry. Remove fat. Cut each chicken breast into five or six slices. Place chicken pieces in a zip-lock bag. Gently pound slices to form medallions, about 2 inches in diameter. Dredge each piece in flour. In a large sauté pan, add 2 tablespoons of olive oil. When the pan is hot, add the chicken a few pieces at a time. Add a little salt and pepper to each piece. Do not overlap chicken. Brown each piece quickly on both sides, about 1 minute per side, making sure the heat is on high. When all pieces are browned, add Marsala. (Important! Use Marsala from the wine department of the grocery store and not the Marsala from the baking aisle.)Turn heat down to medium and simmer for about 30 seconds until wine has evaporated. Add butter, mushroom, yellow and green onions, parsley, salt and pepper. Do not cover. Simmer for 2 to 3 minutes. Serve about 5 medallions per serving. Place chicken medallions over a bed of rice, scooping sauce from pan over chicken.