Dicentra spectabilis Alba (Bleeding heart)
Fritillaria meleagris (Snakes Head Fritillary - white form, without lily beetle)
Also in flower (spreading over the front garden) is the forget-me-not. For a lot of the year I grumble at its habit of spreading, and looking untidy after flowering. But now - so sweet.
Joe Swift has said that green is 'in' in the garden this year. It's not often I'm fashionable!
Polygonatum x hybridum (Solomon's Seal - before the sawfly get to it)
But best of all, April is brash and blousy - bring it on!