Interesting green flower

Thanks SC - I can see where you're coming from. You could well be right. But I have never in 23 years - and four days of living here grown chrysanthemums of any sort.
Got loads of Feverfew though which pops up all over the place. (I can see why Veggie has forbidden me from sending her any!)
I'm going to dig it up tomorrow and overwinter it in the greenhouse (unheated) and see what happens. Will report back if survives.