Andrew F. Smith writes in Potato: A Global History that when the potato came to Europe from South America in the sixteenth century, a lot of people were like, "Nah, keep it." Many herbalists believed that potatoes were poisonous, and other Europeans took the position that if God wanted people to eat potatoes, they would have been mentioned in the bible.
It actually took a decades-long PR campaign to get Europeans to recognize that potatoes are the world’s best side dish/snack/junk food/everything food. Some highlights:
* Legend has it has it that King Frederick II of Prussia (1712-1786) tried to bring the potato to his people, but the villagers were like, "Hard pass." So he had soldiers start guarding his potato field — but told them not to guard too carefully at night — and his efforts in reverse psychology...actually worked?! People began stealing the potatoes and planting them in their own gardens.
* A pharmacist and soldier named Antoine-Augustin Parmentier was a big champion of potatoes in France; after he was captured during the Seven Years War (1756-1763) and survived mostly on a diet of potatoes during his five years as a prisoner, he tried to get the French people excited about their nutritional benefits. He released multiple books extolling their virtues and teamed up with Benjamin Franklin to throw a fancy "surprise— everything you're eating is actually made from potatoes!" dinner. And people were still like, "Naw, dawg." (Er, "Non, chien!")
* Marie Antoinette reportedly wore potato blossoms in her hair and Louis XVI wore them in his buttonhole to try to get French farmers and people hyped about potatoes. (Yeah, I had to re-read the word "buttonhole" a few times too.)