[Flump]

 I don't suppose you could sacrifice a root to show us?

[Puenktchen]

Poppies....

Poppy

Agapanthus is probably right, as you can propagate the perennial poppies from root cuttings, could be planted with the herbs to use the seeds in cooking 

If you mean oriental poppy, I don`t think the leaves are right. Oriental poppy has hairy leaves which are serrated quite from the beginning and not only the older leaves.

I hope someone at the RHS knows the plant. Otherwise there is only waiting for the flowers. With flowers it is often quite easy to identify plants, if you have only leaves it is more like a guessing game.

[Sideways]

Ive had a reply, it is.....

Valeriana Phu. Aurea Herbaceous Perennial, non edible.

I think HilaryG hinted at Valarian, good call!

Thanks all.

[Spana]

Thats really interesting, I learnt something today   I've got  Valerian and the leaves are nothing like your plant.  But if I look at Valeriana in my book thats it, its a totally different plant and  its what you've got.  Just shows what a difference an 'A' makes.

Thank goodness you've at last found out what it is

[Flump]

thank God for that!I had no idea what that was!found a pic that looks just like your bit  Sideways, http://www.btinternet.com/~unusualplants/Archives/apr/valer.html