Dad's right. Some sort of Cucurbits. ie Melon, Squash, Cucumber type plants.

As a community gardener, I do just weed out all and plant my own. Now in my 4th year, I tend to know what the volunteers are, but still start anew. Even if it is a food crop, my personal preference is to make sure I get something I really want and will use with the limited space available. They could be squash, melon, or cuke, but not knowing the variety or if they cross pollinated, it's so hard to tell what you'll actually get. And many community gardeners are new, not knowing what varieties work well with the season, so it could be something with little hope of maturing as well. I meet lots of new garden neighbors who are very enthusiastic, but show up mid may with oodles of seed packets that sound fun, not knowing that they're too late for peas and spinach, need transplants for tomatoes and a trellis for pole beans, or that kind of watermelon won't get enough time when we get an early frost.

Thank you both!! Thanks for the advice, balloonflower. I was planning to plant brussel sprouts in that spot, which wouldn't need to go in until mid-late summer, so I may just let this grow a little while out of curiosity, then pull up if they turn up to be nothing special or it's time to plant the brussel sprouts. I'm just glad to know that it isn't likely a weed, as I don't want them spreading!

I also believe they are cucumber or squash. I have both started for my garden and that is what they look like. :)