Our garden is separated from a local farmer's land by a wild hedge with quite a few elderberry bushes. When the first berries turned black, I did a little experiment and made some elderberry syrup (recipes can be found all over the internet). It turned out really good. The kids drink it with still or sparkling water or use it to sweeten their yoghurt.
Apparently it is a natural cold remedy and gives flu relief and helps the immune system. That sounds good!