Red Clover (Trifolium pratense) 2016-5-31 White Clay Creek SP, DE
Can get really tall - for a clover!
http://www.wildflowerchild.info/search.cgi?hike_id=26
http://www.malag.aes.oregonstate.edu/wildflowers/species.php/id-883
http://www.malag.aes.oregonstate.edu/wildflowers/images.php/id-2125/fullsize-1
"Red Clover has an unmistakable appearance and is extremely common."