I tried to sell the berries without any luck, never tried the flowers.

First, are you sure you have European elder (S. nigra or S. canadensis) and not the native American red elder (S. pubens or S. racemosa)? There is also a blue elder that is edible but the red ones are supposedly toxic even when cooked.

I don't think people would know what to do with the flowers (and they don't last long after picking). I made elderberry jelly last year, but think it's an acquired taste. Elderflower syrup might go over better. Elderflower wine or cordial is supposed to be good, but I don't know what your state laws are on making and selling alcoholic beverages.

The flowers are safe to eat (pick them while they're still white, not ivory) but don't get any stems, bark or leaves in whatever you're making as they are toxic. If you're using the berries, use only ripe black berries - not any green or reddish ones.

I haven't done the research, but wonder, our ancestors used to make elderberry wine out of wild elderberries.

The leaves, twigs and seeds and unripened berries are poisonous, not the berries. You need to be sure to remove all of the seeds.

There is one variety of berries that is not good for you and can make you sick. I'm adding the description for you. It is not a normal elderberry, but a shrub that looks like it.

Avoid elderberries species with red fruit growing in rounded, instead of flat clusters. They may make you sick. Hercules� club is a shrub or small tree with feather-compound leaves that looks a little like the common elderberry. It has flat clusters of poisonous, black berries, often arranged in a ring, and a short, unbranched, thorny trunk. Elderberries are thornless.