Pop. Pop. Pop, pop, pop-pop-pop-pop! It’s Popcorn Day! In the 16th century, popcorn was used in Aztec headdresses in Mexico. It became a popular food in the United States in the 18-hundreds. It’s also Tin Can Day. Peter Durand patented the perfect way to store food for years, in 1810. Eat a tin of popcorn!