The picture is not super easy to see details from but the leaf shape makes me a guess it is Pennsylvania bittercress (Latin name Cardamine pensylvanica). Several Cardamines bloom early in the season.
Below are some pictures and a description, let me know if it fits!
http://cricket.biol.sc.edu/acmoore/herb/CC/Cardamine_pensylvanica2.jpg (broken link)
http://cricket.biol.sc.edu/acmoore/herb/CC/Cardamine_pensylvanica1.jpg (broken link)
Cardamine pensylvanica page
A Wikipedia blurb about it:
Cardamine pensylvanica - Wikipedia, the free encyclopedia