What is this??

If you know me well you know that I have the farthest thing from a green thumb. We have a few plants growing in our front planter boxes that I'm not sure what they are. I think either cucumber, squash or pumpkin. Now, how did they start growing in our front boxes? My best guess is that the seeds got washed up during one of our "floods" in the spring. Kylie told me that we HAVE to take care of them and we CAN'T let them die! She knows me too well....

Does anyone know what they are??