Milk Thistle (Silybum marianum)

There are so many thistle varieties that many people think they are all the same.
No, they are not. This chap right here is the real milk thistle, this is a gorgeous spiky ornamental, famed for thousands of years as a medicinal plant and unusual root, leaf and flower vegetable.

 Silymarin (extracted from this plants seed) is regarded as the standard for herbal liver tonics.
Seeds and extracts are commonly used for treatment of liver and gall bladder diseases, jaundice, cirrhosis, hepatitis, adrenal disorders, candida, inflammatory bowel syndrome, psoriasis, lowering cholesterol, and Amanita mushroom poisoning.
Apparently chewing the seeds on the morning after overindulging can get rid of the general seediness and nausea one experiences as a hangover.
Topping and tailing the plant in much the same way as carrots will force the growth of huge roots, these are a delicacy in parts of rural Europe.
Leaves are edible too, as the thorns are only on the edge of the leaf. Fantastic in salad, and extremely pretty too with the natural, white variegation that gives the plant its name.

You can peel the flower spikes and cook them up to, in much the same way as an artichoke.
The plant will produce masses of flowers and seed within a season. An annual crop, it will need to be planted every spring/early summer.