I could understand if you'd dug up a rare, and expensive, plant but Poppy Heads!
For what it's worth I'd probably tell my DOM (he's not as bad as some)....... knock on the door and apologise to the customer ....... tell him you're not going to be paying him any compensation for "Dead Heading" his Poppies for him (I suppose you could warn him that you've been advised this could be construed as Blackmail, why not contact the CWU Legal Helpline see what they say) .... and learn yet another lesson in life.
Good Luck try not to stress ... it's a killer.