Soilfixer

Some times when you do your normal chores you get rewarded with out warning. This beauty come up among big pumpkins. I plant them (pumpkins) at back of the house in not so fertile soil. Love and good natural fertilizer give amazing results.
This particular plant is a part of special experiment which if (when) successful will revolutionize soil maintenance and increase yield.
So what is this plant?
Can you tell by flower?
I thought it will be good to show the picture and readers try to guess it.
The winner of this small competition will get surprise gift from me.
What are you waiting for submit your answers.