I'm just about to make a batch of elderberry syrup for the winter cold/flu season - I have to make do with dried elderberries for now, but this would definitely be a plant to cultivate down the line. That's a valuable one to have on hand, all right.
The swapping is great fun! It'll be great for you to grow some gigantic sunflowers next summer - the kids will probably have fun with those too when it comes to harvesting the seeds (unless you feed them all to the chickens...)
One of the things I'm noticing about the Steemit community is that if you can find a niche of people interested in the same things you are, it's a much closer-knit bunch than you usually find on social media. I really enjoy the interaction and the amount that's available to learn.