They more than resemble acorns - not all oaks produce lobed leaves.

My guess would be Quercus polymorpha AKA Monterey Oak. Not a native oak but native to not to far away. Many people are planting them because they are resistant to Live Oak Wilt.

No it's not a monterray oak. It's leaves are not lobed like the oak family species. I thought some type of horse chestnut

I guess it's some type of oak tree from a type that doesn't have lobed leaves. Cause those nuts sure look alot like an acorn to me.

Here is a good phot of the UN lobed leaves of a Mexican White Oak.. Does it look like it?

Another photo showing unloved leaves. Judging from the name Polymorha (many forms)LBJ Wildflower Center photo

Here is another non Lobed texas Oak. In this picture it is not lobed , but in other photos there are sedated edges. Oaks will have variation within a species. I have quite a bit of variation in the Q buckley i on my land. Anyway, this is called the Loquat-leafed Oak (Q. rhysophylla). This Loquat=leafed Oak picture was taken in Mexico.

I'm going to keep a watch on the tree and see if it's evergreen or looses it's leaves this fall. So far no indication that it's going to shed it's leaves. The current leaves are alive, and thriving. There is even new growth in a pinkish color baby leaves. There's so much variation in the leaf structure of the oak tree species is hard to tell what it is exactly. But it's an oak, cause I think those are acorns.

Interesting that , in my late night googling , I ran into an amazing oak tree nursery in UK. They had all these rare american and mexican Oaks. It made we real jealous.

Either Mexican White Oak or Loquat Oak...

I have a Mexican white oak. It's leaves have wavy edges. Or a slightly lobed leaf edge. This tree has smooth edged leaves.

If you are in the Austin area, you could try taking the leaves to the Natural Gardener . They have a desk for IDing all sorts of things,... bugs, plants all sorts of things. Barton springs Nursery might also be good.

Looks like the acorn of a Bur Oak, but the Bur Oaks I've seen have slightly lobed leaves? https://www.google.com/search?q=burr+oak&client=firefox-b-1&tbm=isch&source=iu&pf=m&ictx=1&fir=G7_QgE2wU_vUdM%253A%252CoO4G3wi_h3ko9M%252C_&usg=__gJpChq_IUxdQRzNbD-NMzUfNwT4%3D&sa=X&ved=0ahUKEwipzc6Mxr_XAhWKTCYKHfs6DQYQ_h0IpQEwDQ#imgrc=4CHa3Vr1pVfEXM: