Scarlet Pimpernel Anagallis arvensis, AKA Poor man’s weather glass, Shepherds sundial, Change of weather and Laughter bringer. When the flower is open then it will be fine all day, if the flower does not open, then in spite of sunshine being present, there will probably be rain showers.
Following Roger Phillips' example I am now taking pix of the plant structure, leaf style and also when I can side pix of the flowers.

I managed to lift a root and pot the little plant, Hope it will survive but will keep my eyes open and water it if needed. It always makes me think of when some years ago I put a couple of pix on Arcanum Cafe, one of the pix was a seed head. It looked something like a grape, one member asked me if they were worth collecting to eat. I had to point out that they were only about 5 mm in size and it would take quite a lot of them to make a mouthful.

Managed this time to get a side shot showing the calyx as well as the centre of the flower. There is no doubt about it the 10 dioptre lens is good and permits 2 x life-size pix without adding exposure time or f stops. The new 1200 ring flash is performing quite as well as the old one used to,