Another mystery solved

Back in early March, I presented an odd situation: the belief that somebody I didn't know was cutting my grass. Turns out I was right and I found out who and why.
At the time, my theories were that either it was a good samaritan or somebody making a mistake. The answer is that it's kind of the former, but not entirely a selfless deed.
I went out to my mailbox the other day and my next door neighbor was in his driveway. Small talk ensued and I mentioned that I would eventually need to figure out a long-term solution for having my yard mowed. He said, "I've been meaning to talk to you about that." Uh-oh. Is this where I find out I'm the bad neighbor and that everybody on the block hates me? Geez, the grass has never gotten THAT long. "I was hoping you'd let me do that. I used to do it for the lady who lived there before you moved in." Oh. Cool. How much will that cost me? "Nothing..." Nothing? That fits my budget perfectly! "...but I'd like to keep the clippings and use them in my composting." Let's see; my grass gets cut on a regular basis, the resultant detritus is hauled off, I get to take a little credit for helping the environment and it doesn't cost me anything? I know virtually nothing about composting, other than it's like controlled rot to produce fertilizer and that it involves worms and pee and is good for nature. But even if he has a way of turning my yard waste into actual, shiny, spendable American pennies that he uses to make himself wealthy, that's fine with me.