Melt butter in frying pan until onions are slightly browned. Remove from pan. Saute mushrooms in same pan for 3 minutes, adding more butter if needed.
In bowl, combine onions, mushrooms and any pan juices with rice. Add the peas, red peppers, parsley, ham, and shrimp, saving a few shrimp for garnish. Mix lightly and add enough french dressing to moisten.
Arrange rice mixture in ring on serving dish. Surround with 2/3 of the shredded lettuce. Al;ternate slices of tomato and cucumber on lettuce.
Place remaining lettuce in center of ring. Top with reserved shrimp.