I've been growing Oyster-mushrooms on mine for a while now! Actually, ready to harvest my 3rd batch.
In The Netherlands there is an initiative selling growth-kits for this (Rotterzwam). They supply a bag of spores, a bucket and a number of instructions (these are also in Youtube). Really cool if you ask me.<image>
I love this idea. I hope I can find such a kit to grow oyster mushrooms in Indiana.
I once had a scare with spent espresso grounds. I had a rhubarb plant next to my white garage. I was spreading the grounds around the rhubarb. One day in the hot August sun, I witnessed the grounds spontaneously combust. I assume it was the sun reflecting off the white garage onto the coffee. I wouldn't have believed it if i hadnt seen it. Anyhow, i quit doing that.