I thought this was neat enough to show. I was replacing a sidewalk over the week (and learned you need a permit for that) and found this. What I thought was an alien invasion turned out to be hundreds of acorns attempting to grow. There was an oak tree shading my work thankfully.
For anyone interested in a shade tree though this picture is proof how easy they are to grow. Even if you're growing them to eventually cut down as fire wood it's a nice easy 5 year investment. Regardless of their use the leaves that fall off can be raked up and composted along with grass clippings. Fast forwarding to a year later you have a reasonable amount of nitrogen rich soil to grow food with and improve your soil.