Cut cooked chicken or sweetbreads in half-inch cubes; remove the skin and seeds from white grapes, and cut each grape in halves; cut tender blanched celery stalks in small pieces. Take equal portions of celery and meat and half as much of seeded grapes. Mix with French dressing; the meat should stand in the dressing an hour or more, when ready to serve. Serve in nests of lettuce. Dispose a little white mayonnaise or cream dressing on each nest. Garnish with halves of blanched pistachio nuts.