Native Bluebell (Hyacinthoides non-scripta)
If you search carefully amongst bluebells you may be fortunate enough to find the odd whitebell.
This white one below I found in a woodland area.
I found it in the same place as previous years so its still growing well from the bulbs. It does have a tinge of blue on the end of the flower although that disappears when fully out.
It may not be a true whitebell however, which is extremely rare.