It looks sorta familiar, but, I just can't put my finger on it. It was folded in half when I found it. I straightened it out for the photo. It's about 3 1/4" long (85mm), 10mm wide in the center, and 18mm wide on the ends.
Maybe a old ground strap for a old radio/TV ? Seen something similar on the floor of a TV antenna station out in the sticks I delivered bottle water to many years ago. Just a shot in the dark.
Your find is part of an outdoor electrical service drop wire clamp, used to provide "strain relief" for the electrical wire. Some are made of copper, and some are aluminum. See the photos below.