Tiny little things, one flower head about 4" across has over a hundred, mostly seeds. One plant might have 30 flower heads.
Takes about 1.5 billion to make a small pie.
You take an entire head of ONLY ripe berries, the green ones are poisonous(as is the rest of the whole plant), work the whole thing into your mouth and pull off the berries with your teeth/lips, trying to leave all the stems behind. Chew to get the juice and pulp and spit out the lump of seeds.
Was coming home from the cottage today I had about 10 elderberry heads, a handful of wild apples and a wild rosehip.