Robins and a plant id question

I was cleaning out a flower bed in the front yard last week and leaned up against a crepe myrtle to rest. The tree shook, I was unaware that there was a bird nest above me, and three robin juvies flew out. The mama and the poppa were around too, and went ballistic. Sorry birdies, I didn't know you were there.Plant identification is scienceThis plant and another just like it came up among the hills of squash in the garden. None of the gardeners know what it is. It has a really pretty flower.The leaves have an almost rubbery feel and the entire plant is covered with a sticky substance that gets on your hands.A fruit is beginning to develop.They think some seeds must have mixed in with the squash seeds.