Easier to say what one could NOT eat. There were of course no New World vegetables. No potatoes, pumpkin, tomatoes, peppers, peanuts, beans, sunflower seeds, squash, sweet potatoes and worst of all no chocolate.
No swede - some advantages after all. No African fruit so no melons. Dates, coffee, oranges and lemons were brought back by Crusaders,
Other things were not eaten much as they had not been developed to a size we know today. Carrots for one. They had the disadvantage of the plant's resemblance to Hemlock, a deadly poison.
Honey was used for sweetening. Hives had to be destroyed to harvest the honey. Of course there was mead to drink, as well as wine and ale. It has been calculated that without the extra calories provided by the ale, many would have starved. Nowadays, it just gives us beer-bellies.