What's this little plant?

[MrsBertBibby]

I feel like I know it. Very distinctive geometric look to it, but I can't place it.

Caper spurge?

I have this on my plot. Don’t know the name. I dig it up as it can get quite big. Not helpful, sorry!

Yup, caper spurge aka Euphorbia lathyris. They can pop up out of nowhere!

Thanks all. To the compost heap it goes.