Peanuts contain approximately 25-28 grams of protein per 100 grams, which is the highest among common nuts listed. Almonds have about 21 grams per 100 grams, while cashews and walnuts have lower protein content at around 15-18 grams per 100 grams. Peanuts are legumes, not true nuts, but they are commonly grouped with nuts and have the highest protein content.