Where did it come from? City?

Boulder, Colorado. I'm quite sure it's not native. Anyways, as luck would have it, I was able to get a rather grainy snap shot of the exact tree that I got the acorn from off of bing maps street view. The tree happened to be right next to the road. Here this might help:

Here is a link that might be useful: {{gwi:332765}}

well, the foliage in the picture seems to be that of some kind of red oak---quercus rubra for example???

I'd say red oak of some type. The acorn is darker than I'm used to seeing but it just could be the camera.

I meant to say the acorn is darker than the ones I normally see on Quercus rubra

The acorn was lighter in color when I first picked it up. The one in the picture is dark because it has been in the frige all winter with several others that are now outside in pots. Anyways I'm thinking it's either that or Quercus shumardii.

Scarlet Oak is a possibility given the shape of the tree/seed.

Dax