A relatively good alternative to nuts, for those who have allergies or simply don't like the taste, is a type of legume commonly referred to as a pulse.
Pulses include lentils, dry beans (e.g.: kidney beans), chickpeas, lupins and many other varieties of legumes. What these foods have in common to nuts is a high protein and fiber content. But they don't provide a source of healthy fats so they do differ from nuts in that regard.