This is a type of Eleagnus, sometimes called Silverberry. The giveaway is the silver-backed leaves and dotty markings on leaves and fruit.
Originally introduced as an ornamental, a couple of types have become serious invasive threats in our area. You can see them growing in thickets along many of our highways. The silvery leaves often flash in the breeze.
We can't tell you what kind as there are so many, though if it is thorny, it could be Eleagnus pungens, which is from China and Japan.