Just going by the foliage I guess some kind of kohlrabi, kale, kabage (Brassicaceae) ,

pepper would be from the night shade familiy, and I consider that highly unlikely.

The seeds of the cabbage group tend to be long lived and could pop up after turning the soil, repotting etc.

Let's see what others can narrow down, bye,

Lin

I didn't mean that it is a pepper but the seeds were mixed in with the potting soil of the pepper. Sorry for the confusion. The closest plant I have seen that looks similar is a rutabaga.

What about Raphanus sativus, the foliage looks very similar.

As they hybridize very easyly among eaach other, there could be all kind of variation and different shades/ colors.

O, and what does is smell like, did you taste it?
Bye, Lin

Here is a link that might be useful: {{gwi:357314}}

Definitely not kohlrabi.

It smells mostly earthy, not too much smell. I broke off one of the smaller roots and chewed it. It tasted spicy similar to a radish. Maybe it is some large variety of radish?

There are some really large, old varieties of radishes which are meant to be harvested at several inches across. (The average small radish would crack long before it reached that diameter.)

The one I grew once was Black Spanish Round -- black because the skin was black rather than the usual red, white, pink, or purple. They can be cooked or eaten raw, or stored in the basement. IIRC, there are others which are long in shape rather than round (Black Spanish).

I believe there are similar large radishes with white skin, but I haven't grown them, and I don't know if their skin would be as smooth as the one in your photo, or as tough and fibrous as the black ones I grew.

You might also ask on the Vegetable Gardening forum and see what they think. It would be a good idea to tell them the diameter of your mysterious root, as well as when you planted the pepper seeds
http://forums2.gardenweb.com/forums/cornucop/

I've had weeds here (not in the area of the veggie garden) which seemed to be some sort of wild turnip. The appearance of the leaves, flowers, and pods certainly shouted "Cabbage family!" The root was a wide triangle. But I was never tempted to eat one.