Had roofers redo the roof awhile ago. I checked the lawn for errent nails thinking I'd find none or two. It went from mildy to infuriating.
Did the same. I've got kids running around and told them, before starting, it was important I don't have a yard full of nails. I found about 50 and demanded them to sweep again. Even after that I found more. I decided to pay my kids $1 per nail, so they scavaged and found more heh.