horseradish

jarred and labeled. i'll keep one jar in the fridge for us, one jar in the freezer and the others are spicy little gifts.
the words "do you want some horseradish?!" to a gardener are usually met with the same wide eyes and inner panic as when someone says "do you want some zucchini?!"
but when you say you've prepared and jarred it they seem to be willing to give it a try.
horseradish root is great for building up some crappy soil, but good luck getting rid of it when you want to make room for something else.
oh! and the leaves make a delicious pesto style sauce, or can be pulled and left as mulch and overwintering beneficial bug protection.