Note the "askew" or asymmetrical flower part. found in flood plain of ohio river; plant trailed over ground.
Apios americana ? http://floridanatives.files.wordpress.com/2010/07/groundnut_2583_2.jpg or Amphicarpaea bracteata? http://www.minnesotawildflowers.info/flower/american-hog-peanut
Amazingly variable foliage. Thanks for getting back with the ID. http://www-personal.umich.edu/~rburnham/SpeciesAccountspdfs/StrohelvFABAFINAL.pdf