Certainly looks like an opium poppy seedhead but I doubt it would be possible to identify the exact variety - they are very promiscuous!

Just been through all my pictures of P. somniferum (226 of them) and can't see any where the seed capsule looks like that.

Even when the flower is just opening the capsule has the starfish type structure on the top standing away from the sphere of the capsule itself.

Also, all of the 'fronds' around the capsule have white tips (though it may be yours have gone brown).

I was thinking that it might be a form of Shirley Poppy (P. rhoeas), myself.

Tug I have had a look at the P rhoeas and it could be that. It is a pity that it was not more mature when it keeled over. Is it worth holding on to the seed pod in the hope that I get some seed from it? Thepoisongardener I think these frondy bits have always been dark and the stems of each of the fronds is a deeper pink. It is hard to decide if the leaves are right for either suggestion as it has flowered in its first year, I did not expect it to flower until at least next summer

Both Breadseed and Shirley poppies are annuals, and I would expect them to bloom the first year from seed. Oriental Poppy (P. orientale) usually waits for the second year, but rarely might bloom the previous fall. If it is an Oriental, then the flowering stem grew out of a dense tuft of perennial shoots.
As for the seeds, the pod looks much too young, but hope springs eternal.

I have added a photo showing the seedling plants when I potted them on if this is any help. I sowed some of P.Som. Purple and although I said they are pink, looking through photos on the web they do look similar. Interestingly Thepoisongardener there are photos of the same plant showing both white and brown tips.

A quick update. The tuft of leaves is growing away again. It is still in a pot so I will plant it out in the garden when I clear a space for it. It has overwintered outside between the greenhouse and a shrubby area.