Bilberries — also known as European blueberries or huckleberries — are little blue-black berries that grow on small, wiry shrubs above the ground.
You'd be forgiven for confusing it with a blueberry, but the two fruits are different. Whereas blueberries are light green inside, bilberries have a deep blue-purple-coloured flesh, and are much juicier.
If you want to forage for bilberries, they can be found in later summer and early autumn. However, they don't grow in great quantities, so they can be hard to find.
If you're lucky enough to spot some, you might find it takes time to pick the berries by hand, but their deliciously tart taste and health properties make them well worth it.