This is an (old?) oak that lives in the yard beside the house. Worms eat the leaves a lot but there's a new problem: I found a lot of leaves infected with these knots! Anybody know what's wrong with it?

I’m think one of the galls. Leaf mite gall, something along those lines. As far as I know, it isn’t anything to worry about or take any measures to control.

Looks a lot different than the white and red oaks around here.

Looks like a Post Oak.

https://www.wildflower.org/plants/resul ... plant=QULY
Overcup oak is another possibility.

Oak leaf blister?

I don't know what galls start out looking like, but they turn into large spheres, here.

I'm not sure what kind of oak it is, it gives small, light brown acorns that attract the mice to the yard. It lives beside the house and give nice shade, so I'd hate to lose it. But worms eat the leaves a lot I remember one year the ground surrounding the tree was full of work poop.

https://neilsperry.com/2013/10/texas-tr ... oak-galls/

Lots of kinds of galls on oaks. Post Oaks get a leaf gall.

Oak trivia.
One of the largest oak forests in America is out by Monahan's Texas.
Ball moss and Spanish moss that grows on oaks aren't moss.
They are kin to the pineapple in the Bromeliad family.

Oak wilt? We have it in Wisconsin.
https://dnr.wisconsin.gov/topic/foresthealth/oakwilt