Finally:

What's the stuff at the bottom?

@JourneymanGeek Rhubarb crumble. With vanilla ice cream.

Harvested from the plant at the top.

Ah!

Its not something we see here

Yup

and I guess it dosen't ship well/we have no clue what to do with it...

It’s quite tart, so usually you add quite a good amount of sugar. So basically the same as in lemonade - sour + sweet = delicious.

And it gets cooked. Then it softens rather quickly, if you keep cooking you get a mush.

Caramelized in a pan is a non-traditional but delicious preparation.