A hickory nut is the hard-shelled, sweet, oily seed of a hickory tree (genus Carya) — the same North American genus that gives us the pecan, its larger and softer-shelled cousin. The prized eating kinds, above all the shagbark (Carya ovata), yield a small, pale-gold kernel that tastes like a richer, more intensely nutty pecan — buttery, sweet and deeply woody — locked inside a thick, four-ribbed shell that is famously hard to crack.