What can you do with rhubarb, food wise?

Wow! I almost think you're joking! Rhubarb is one of my favorite foods :-)
My favorite is rhubarb crumble. Anyway, mixed with sugar & cooked, it
absolutely divine. Many people also make pie from it. There are many recipes
that mix it with strawberries. Use the stalks. Throw the leaves in the
compost pile (they are poisonous). Google for "rhubarb pie", "rhubarb
crumble", or "rhubarb crisp."

how about potatoes

Potatoes are pretty plants, similar to tomatoes (same family). I guess it
depends on how you plant them. You'd want it to be in a place that can
easily be dug up. (and probably not too many plants together) Or, you could
plant them in some sort of raised box, which I think would look very nice..

Come to think of it, you could even make cabbage look good, surrounding by
some different, smaller plants. (and there ARE ornamental cabbages, though I
don't know if they are edible)

Kohlrabi is also a very interesting plant. Some may think it is ugly, but
planted in a designed, complimentary setting, can be quite the unusual
addition.

Oh, and don't forget that some flowers are also edible, such as pansies.