What's this plant? - prairie dock

I've been unable to identify this plant. I've got an inexplicable
compulsion to identify any plant that catches my eye....

Yellow dock I think

The leaves are very stiff and fibrous. Maybe more tender in spring.  Plant is very woody and sturdy.  Is dock like that?

Looks very much like the horseradish that's gone wild at my place.
Dig up a root and smell or maybe just smell the stalk.

Here is a picture of what I believe to be yellow dock.  I can take another pic when I dig up the garden next time.

No horseradish smell. Just woodsy green.

Looks like a species of Dock, Rumex.

http://www.eattheweeds.com/rumex-ruminations/

My guess would be prairie dock...

Yellow dock is common on my farm but I planted quinoa and I am having trouble telling the plants apart.  Hope the seeds will be easy to differentiate.

I agree with John, pretty sure that plant is prairie dock.  We have a  lot of it here in the Ozarks.

Definitely a dock (there are many). It is generally a sign of acidic, at times wet soil. It does a great job of accumulating calcium and iron, which it provides to livestock or compost teas. I bet it also adds a good amount of nitrogen and potassium. I have used it to combat calcium deficiencies in my fowl and tomatoes.