Carex demissa Common Yellow Sedge C DD N
As with most sedges it grows in wet or boggy places and this one has bright green fruits which stand out against the usually dark background. This one is very common in Scotland and most of England and Wales but is less common in the east of England.
The name has recently changed (New Flora of the British Isles Third Edition by Clive Stace 2010) from Carex viridula ssp oedicarpa to Carex demissa. It was Carex demissa before that so older books will appear to be up-to-date.