Is a peanut a “nut” or “legume”?

Peanuts are legumes!

Yes. Peanuts, along with beans and peas, belong to the single plant family, Leguminosae. Legumes are edible seeds enclosed in pods. As a group, they provide the best source of concentrated protein in the plant kingdom. While their physical structure and nutritional benefits more closely resemble that of other legumes, their use in diets and cuisines more closely resembles that of nuts.

Where do they fit into the food Pyramid?

Today peanuts are classified in the USDA Food Guide Pyramid with meat, fish, poultry, dry beans, eggs and nuts because of their high protein content. However, because peanuts are plant-based, they do NOT contain cholesterol and some of the saturated fat that is found in animal-based sources of protein. In fact, they contain a much higher percentage of the "good" unsaturated fats than saturated fats. Therefore, peanuts have been placed closer to the bottom of both the Mediterranean and the Vegetarian Food Guide Pyramids, in the eat daily category.