Those two upright disks lay down and make marks telling the farmer where he has been. The seed corn would be in those two hoppers in front.
I have painted and drawn this thing many times, but it never fails to catch my eye with all its angles and protuberances and hints of rustic history. This time I caught it in the orange afternoon sun of December. I couldn't figure out how to capture the orange glow on the rusty metal, so I broke from my usual practice and overlaid a little red prismacolor pencil here and there. That did the trick.