Residents of New England, especially Maine, may not think these are exotic. They are a traditional vegetable dish throughout the region, occasionally served boiled, in a salad or with mayonnaise or butter. For the rest of the country, though, fiddleheads probably look more like alien appendages than a vegetable.
They are actually the furled fronds of a baby fern. One reason they're so rare outside of their native regions is that they are not cultivated — only harvested from the wild — and so are only found locally and seasonally. Foraging for fiddleheads is also for experts only: Much like with mushrooms, not all ferns are edible and some are poisonous.
They are packed with nutrients and acclaimed for their succulent flavor. Fiddleheads are full of omega-3 fatty acids and fiber, and contain twice the antioxidant quality of blueberries.