FWIW, I saw something similar on my place way back in the day. I have grain bins that I have sometimes rented out to local farmers and I can tell you that local deer come to know where they can get some "free" corn to eat when it gets really cold. I found a modest single antler in the yard once, about 10 yards from the spillage. Yours may have been knocked off by the fence guarding the auger. Nice.