(also known as Hazelnuts) These wild NUTS grow in clusters on the hazel tree in temperate zones around the world. The fuzzy outer husk opens as the nut ripens, revealing a hard, smooth shell. Italy, Spain, France and Turkey lead the way in hazelnut production. Until the 1940s, the United States imported most hazelnuts; however, they're now grown in Oregon and Washington. Also called filberts and cobnuts, particularly when cultivated, these sweet, rich, grape-size nuts are used chopped, ground and whole in all manner of sweets. They also add flavor and texture to savory items such as salads and main dishes.