It looks like some kind of thistle. One that I would call a weed, but its pretty.

It is salisfy, a root vegetable, in its second year as a biennial when it's flowering. The flower will only last a day and then it will set lots of dandelion like seeds that you can collect to sow more.
In our garden it has 'naturalised' in one part of the garden and we get a beautiful show of these purple flowers all through May and early June.

Sorry meant to tell you that you can steam the unopened flower buds as well, which are quite tasty.

Wow this really is the plant of the year - we have had so many questions about...

Salsify it definitely is. Thankyou to all who replied. At least it came up in my kitchen garden which is convenient.

But never fear it will travel further if you let too many seed heads disperse. Mine travelled over two hedges, a couple of tall shrubs to get from the border to my plottie where it is romping away in compacted solid paths.

Yes, MG, It's strange - all these questions pertaining to salsify; they meant it was unnecessary for me to ask the same thing about a month or two back. We have always had them growing in by the sides of the road round here, but this year there seems to have been an explosion of them. The locals are frequently seen out with their little forks and a basket, harvesting them - food from the wild!

Haven't eaten the roots in years but they taste good!

I've never tried them. Maybe I should get out there with my own little fork!

One of the plants common names is vegetable oyster Gattina.

Well, I am fearsomely allergic to the marine variety, so maybe this could be the answer! I wonder if that means it tastes the same?

Supposed to, can't remember to be honest.