This vine (see http://home.comcast.net/~kerrysuz/mysteryVine.html) has been growing in our yard for about a month. At first we suspected it was a squash or cucumber dug up by a squirrel and replanted (because some of our cucumbers WERE missing, but the squirrels were nice enough to replace them with sunflowers...ha), but the leaves of this vine don't match anything that we have, and it's not producing any fruit. It is also very sticky when touched, and its tendrils really get a hold on things!!! So without any fruit, we're having a lot of trouble identifying this.
I live in Marshfield, Massachusetts.