Greater Stitchwort aka Stellaria holostea and a common hedgerow 'weed'
that is a very superior cousin of the common chickweed or marginally
lesser cousin of the garden pink - make your choice. I like to see it
and it makes a nice, lowly boscage of pleasantly leafy stems topped
with rather showy white flowers at this time of year. It is very
obvious for a couple of weeks and then disappears into the the
undergrowth until the following spring.