Grilled Chicken, Butter Lettuce & Citrus Salad with Feta Vinaigrette

1 head butter lettuce, washed, dried, and torn into bite-sized pieces 1 grapefruit, or two oranges, or 4 tangerines, cut into sections, membrane and pith removed 1 chicken breast, grilled and cut into strips 1/4 c. kalamata olives, cut in Read on!