Sorry! That's the wrong answer. This is Buttercup, a yellow flowered weed which is very common throughout North America, particularly in wet areas. Buttercup include tall (2.5 feet), creeping, meadow and celery leafed varieties.

Buttercup contain irritant juices that severely injure the digestive system. Sap from stems can cause inflammation and blistering on skin or mucous membranes and even around the hooves of horses used to harvest. Note: poison is inactive when buttercup is dried and included in hay.