I love this plant. The bees love this plant, no idea what it is or where it came from so guessing its a weed
Welsh poppy, Meconopsis cambrica.
How can you lie there and think of England
When you don't even know who's in the team
It might be an Iceland poppy (papaver nudicaule). That's my guess anyway !
Looks like the Californian poppy - Eschscholzia. It's not a weed but seeds really easily and tends to want to take over, popping up everywhere, but it is easy to remove so i don't think it's a problem.