Saw these growing at the edge of my grass lawn. Haven't seen these before, and a quick Google search doesn't yield anything familiar in terms of weeds.
I downloaded a rather good app the other day called PictureThis which tells you which plant is which when you take a photo of it.
There is a free trial but I've just let mine run as I'm useless with plants and it's been fun for the kids.
I recommend the PistureThis app - but it's rather better at identifying tree types and with the millions of flora types it cannot id everything - still useful though - I found a tiny oak and an ash tree growing in my garden!