What is this?

Something made me think of this today and I wondered how many people out there would recognize it right away.

Then I got to thinking of my 6th grade teacher. Once a week she would hang up a magnified picture. The class would have one week to enter their guesses. The fewer the winners, the larger the prize.

Today's pic is not magnified. I just want to see who comments first with the answer.

Later tonight I will begin a real game with real prizes!

What is this?