This plant is the yellow form of the common snowdrop. Very variable in the intensity of the yellow colouring and can range from a pale, limey-green to an intense egg-yolk yellow. The leaves can also vary in the degree of yellow pallor.
Below is the ex Lowick form
The following photographs are by courtesy of Mark Smyth. The first two show a mixed colony of galanthus nivalis growing wild in Scotland; the third photo is of a superb clump of sandersii growing in a private garden.