In lieu of many spices, golden treasures and precious gems early Spanish explorers returned to Spain with items of much greater significance: tomatoes, potatoes and corn. Unfortunately for those who financed the voyagers, the value of this produce was not immediately appreciated.
The Spanish and the Italians hailed the tomato (whose name comes from the Aztec tomatl) as an aphrodisiac-perhaps because of its resemblance to the human heart- when it arrived from the New World during the 16th century.
But even though tomatoes soon become part of Spanish and Italian cuisines, most other Europeans, New World colonists and later, Americans considered tomatoes poisonous. (There is some truth to this notion: tomato vines and leaves contain tomatine, an alkaloid that can cause health problems.) Thus for many years and in many societies, only the adventurous ate tomatoes. Tomato historians consider September 26, 1820, a red-letter day marking the popular acceptance of the tomato.
On that day, the then-well-known eccentric Colonel Robert Gibbon Johnson ate an entire bushel of tomatoes on the Salem. New Jersey courthouse steps before a crowd of thousands -and lived. Tomatoes soon became one of the most popular of all vegetables.
Similarly, the potato, first delivered to Europe from its native Peru by Francisco Pizarro in die 16th century, did not win wide acceptance in haute cuisine until Antoine-Augustin Pamientier (1737-1813), a French army pharmacist, induced King Louis XVI of France (reign 1775-1793) to try one. He and his courtiers liked them so much they even began wearing potato blossom boutonnieres.
Pamientier was ultimately honored for his starchy contribution to French cuisine by having several potato dishes named for him, such as potage Pamientier (potato soup). Not only did Pamientier lobby for the acceptance of the potato as a food fit for a king, he also prophesied that the potato would make starvation impossible.
Potatoes ultimately did become a staple of many diets. But, sadly, the converse of Paniientier’s prophecy came true during the Irish Potato Famine of 1846-1848, when a terrible blight destroyed the potato crop. Nearly 1.5 million people died, and an equal number emigrated to the United States. They brought with them a cuisine that incorporated potatoes; thus an appreciation of the common potato was reintroduced to its native land.
When returning from his second voyage to the New World. Columbus took corn with him. Called mahiz or maize by West Indian natives, com had been a staple of Central American diets for at least 5000 years. 
Although Europeans did not actively shun corn as they did tomatoes and potatoes, corn never really caught on in most of Europe. (As with another famous New World import, corn’s origin was mistakenly attributed by the British, Dutch, Germans and Russians to Turkey. They called corn “Turkish wheat”: the ‘lurks simply called it “foreign grain.”) Grown for human consumption mostly in Italy, Spain and southwestern France, corn was and still is usually eaten ground and boiled as polenta.
But despite an unenthusiastic European reception, corn’s popularity quickly spread well beyond Europe: Within 50 years of Columbus’s journey, corn was being cultivated in lands as distant from the New World as China, India and sub-Saharan Africa.