I really should know what this is.....but I'll let the others venture a guess. Wouldn't be fair to guess as I've been by it hundreds of times!! I will say you've given it an appropriate place, exactly what I would do with a find like that!!!
I'd say a disc, too. But are both those wheels from the same thing? They are both different but look like they are on that machine together. I love old machinery, too. We had my hubby's dad's old push plow for the longest time. Til the wooden handles fell off. I'd love another one to really use in the garden.