1. Polygonum sagittatum perhaps.
2. Apios americana
3. Sium suave ?
4. Polygala , P sanguinea?
5. Trifolium dubium

Here is a link that might be useful: Sium suave

This post was edited by carol23 on Sun, Aug 11, 13 at 21:30

Wow, That is great. Carol23, after looking up your suggestions, I am sure you nailed 1,2,4 and 5.
Number 3 has to be close, but every description of sium suave says "margins are finely serrated." This one is smooth except for the odd tooth on each leaf. The plants were only 2-21/2 feet tall through out the field and it was very wet with some standing water.
I appreciate all of the ID's.

I am posting a close up of one of the clusters in the flower 'head'. Each is a rounded like a golf ball.
{{gwi:324592}}

Oxypolis rigidior?

Here is a link that might be useful: Oxypolis rigidior

5. Looks like Medicago lupulina to me.

Here is a link that might be useful: hop clovers