Normally Hairy Violets (Viola hirta) do not grow in wet places, but here it grows near a stream amongst yellow Lesser Celandines (Ficaria verna).
Small spring violets are much alike. The difference between species is in the details.
The Hairy violet has rounded sepals...
... and, as its name says, hairs. You can find them on the new leaves, but they are very short and nearly invisible if you don't use a magnifying glass.
Here are some plants growing amidst dead ferns at a wood edge, the usual habitat for this species.