Clean mushrooms with damp paper towels.
Remove mushroom stems, and reserve for other uses.
Cut each heart of palm into thirds.
Place a piece of heart of palm in each mushroom cap, to look like the original mushroom stem.
Arrange the mushrooms on a large lettuce-lined serving plate with "stems" up.
Drizzle salad dressing over each mushroom.
Cover and chill 10 minutes or until ready to serve.