There is some basis for some crops being seen as poisonous. Tomatoes were originally considered an ornamental in France. When the Portuguese introduced maize to some populations and they based their entire diet on maize they got sick, they never bothered to ask the natives how they prepared maize to avoid this issue. Other cultures such as Hungary made their own cash crops by making spices like paprika from peppers and sending it on down the Silk Road. I think Hawaiian Pizza is the perfect example of the Columbian Exchange. Pineapples aren't from Hawaii and Pizza along with most of it's ingredients and toppings aren't from Italy.
