It is definitely not a snowflake...Leucojum.
It might be Allium family...maybe wild garlic.???
What were the leaves like?
Try picking a leaf and crushing it. Does it smell of onions.
Another suggestion is Anemone nemerosa...wind flowers.
A low growing plant with cut leaves.
Both these would be found at this time of year in a UK woodland with bluebells.
It is always helpful to see the whole plant/ open flowers/leaves plus something to give scale...a coin, lens cap/hand.etc...
Do please add more pics to this thread.
A single pic showing one tiny flower is not sufficient for an accurate id.