mystery plant

Anybody know what this plant is?  It smells extremely bitter, and when I tore off part of a leaf it oozed juice similar to that of dandelions and cat's ear...

May be a "dock" in the rumex genus

Looks more like a mustard to me. 

It does look rather mustardy, but I don't think it is!  I don't think it's a dock either...

You'll probably have to wait until it blooms to get a better idea what it might be.....

Docks and mustards do not have milky, gluey sap.  Some lettuces do, but I can't name it from the pic.  What part of the world is it growing in?

It looks familiar. what about thistle type plants, and dandy lion type plants. rose.

I've never seen dock or musterd with white sap, only clear.

homesteadpaul, I am in the pacific northwest

it looks like the sort of weed that grows a rosette of leaves at ground level the first year of its life while it puts down a long root and then sends up a big flower stem and flowers the next year. A bienial weed. WHat is that you have growing next to it parsley and dill or some such.
  As a weed with a deep root t should be one that is good for your garden if you have space for it. agri rose macaskie.