Could it have been a piece of shell? We kept canaries when I was a kid and they always removed the shells after the chicks had hatched.Talking of broody (not a chicken)
The garage door has been left open a lot recently because it is a convenient place to store tools to build the Chicken Palace. As a result I acquired a broody visitor - and now I have babies!
I think this is Papa bird checking in on the nest and I see two babies and the mother in the nest at the back. She leaves the nest periodically during the day and both parents are back and forth a lot. He seems to sleep elsewhere and she sleeps in the nest.
I am not sure what they are - my current best bet is a Carolina wren. They are quite bold and are around me while I am working around the garage.