I discovered several big red elderberry plants on my bike ride the other day. After a fair amount of reading, there is a lot of information out there about how it has some toxicity in the stems, seeds and unripe or uncooked berries, so it seems a little sketchy.
I gathered a sack of berries and when I got them home, worked hard to pull the berries from the stems. I put it in a slow cooker for a few hours while I slept. I woke up in the night to a strange and powerful smell and panicked a little after reading one bogus-sounding comment about how the fumes from cooking the berries could be toxic. I went downstairs and removed the berries from the heat and went back to bed.
The next morning I processed the berries with a food mill, which left a few seeds in the juice, so I strained the juice again using a nut filter bag. This left me with a nice bottle of red elderberry juice. I tried a small glass of it. It is a bit thicker than a typical juice, and tastes almost exactly like orange juice that comes in a small tin can, something I haven't seen since I was a kid. So far it seems like decent stuff, except for the fact that it neither smells, tastes, or looks particularly pleasant.
Update from a few days later:
After drinking a small glass of the red elderberry juice that day, I found the memories of the taste to be increasingly unpleasant. Today I got in my car and could smell reminders of the flavor and it's a real turn-off. I think I may dump the remaining juice and try to forget this experiment ever happened, and from now on, leave those red berries on the bush.