The light green serrated leaves in the middle are a hackberry tree that was planted by a bird. They have a bad reputation, but they're fast growing, native, and provide decent shade. If this is at least twenty feet from your house, you could let it grow and have a tree there instead of a mystery shrub.
You can confirm it's hackberry by looking at the veins at the underside of a leaf. You should see three main veins starting at the base of the leaf, similar to if you held up your three middle fingers.