The early twentieth century was the heyday of doing all sorts of things with mayonnaise or gelatin or both. These recipes often involved lettuce, too. Some were variations of the old-fashioned aspic found in Victorian cookbooks, many were salads, others were desserts -- or a combination of any two of the previous categories -- and some are undefinable.
Many of this type have started out as promotional recipes for companies that sold one or more of the ingredients. Some have become traditional in families, a must for Thanksgiving over two or three generations, and a few of these ideas, such as the use of ginger ale in gelatin, have attained the status of "classic" more widely.

Chicken Gelatin
Frozen Fruit Mayonnaise
Ginger Ale Salad
Prune Salad
Winter Salad