they are probably some commercial hybrid. Probably proprietary. The f2 generation would probably be different too. You can get similar results with the sweet 100's hybrids out there.

A common question on the Growing Tomatoes forum and it has no answer. As mentioned the odds are 99% they are some hybrid and so probably won't grow true from seed. But you can always save some of the seeds and give it a try if you wish and see if you like the results. All the instructions for how to do it are on the Growing Tomatoes forum here.

Dave

Just looking at a handful of fruit we can say with some confidence that they are cherry tomatoes. Beyond that, you'll need to get out your DNA analysis kit. If you're after some particular characteristic of these tomatoes you'd do well to consult the many review sites for tomatoes to learn about what variety has that characteristic.

You'd be better off buying a pack of seeds or some tomato starts. I replanted tomato volunteers a few years ago. All excited about having free plants. They tasted nasty and the skins were like leather. Not worth the time and effort I put in to grow them. Only heirlooms grow true from seeds.