They look like californian poppies....please don't ask me to spell the latin name

Well Badfish, I've gone through the empty seed packs in the shed, and right enough. an empty pack of Californian Poppy. (A magazine freebie I think). I don't remember putting them in, so I wonder if they actually spilled out of the opened packet ???? Well done, thank you. I wish seed packs had a wee picture of the seedlings on them for identification.

I agree, its Californian Poppy (Escholzia). I have some myself.

If you have an empty packet it will have grown from a dormant seed - they self seed very readily.