mystery squashes

This year I have a bunch of squash-type plants that volunteered in my community garden plot. One of them sprouted from my compost bin, and is growing out of my fence and into the path. No fruits yet. I am curious to see what it will produce. The others are a clump of three plants in the far corner of the plot where my compost bin was last year. They are BIG plants that sprouted early. The fruits are forming and look like Big Rock pumpkins.