I got free kittens once simply because the cat I already had as a pet got pregnant and had kittens. I did nothing to get the kittens, did not pay the Tom cat, did not take her to the vet or give her anything extra, she may have eaten a little more, but the cats get free choice food,so who knows. If I had a show chicken that just happened to lay eggs (as they tend to do) without me paying more for a chicken that lays eggs versus one that doesn't, then that makes the eggs free provided you were going to have the chicken regardless of if you got eggs from her or not.
I suppose it is all in your perspective!
Lucky you for having such an interesting outlook that you get "free" eggs out of it!

I wish MrB thought the same way.

MrsB