In Denmark, country folk held that if you stood under an elder at midnight on Midsummer Eve, you would see the king of the fairies and his court.
The juice and flesh of ripe common elderberries are edible, the stems, leaves, seeds and unripe berries contain unsafe levels of cyanic glucosides. So all elderberries must be cooked before eating. They don’t taste very good raw (they are bitter), so most people would not be tempted anyways.
A handful added to an apple pie gives it a lovely color and a piquant flavor. Most people have at least heard of the delights of elderberry wine.