I'm running at around 1 for 5 on IDs lately, but I labeled a photo of this tree next to the Parks Board Building's parking lot as Quercus x turneri one year, and I still think it's that. Of course, corrections are always welcome. Here is the photo from 2014 with some full-sized acorns.
Looks right to me. One thing that's unusual is to see it producing acorns - seems to be a very shy seed producer usually.