Observed on the first Friday of June each year, National Doughnut Day has become something of an American staple. Smaller restaurants and national chains use the occasion as a celebration of all things glazed, jelly-stuffed and cream-filled. The Salvation Army actually established the holiday in 1938 to raise funds during the Great Depression and pay tribute to the female volunteers who served American soldiers meals during World War I. Today, millions of doughnuts will find themselves on....