Hi. I'd like help identifying a (vegetable?) plant.

I got a load of organically-rich topsoil for a new lawn. The leftover topsoil started growing something. Several people told me that it's some type of squash, but I cannot find pictures of squash/melon/zucchini that has a single stalk. Everything seems to be bush-like or vine-like.

Details that might help: 1-inch wide yellow flowers have just started blossoming. The biggest leaves might be 6 inches across. I am located in central Connecticut. Please see the attached picture. Any other info needed?

Any help would be appreciated. Thanks.