The item above, for those 'city slickers' who may not know it, is a mower. Some call it a sickle sidebar cutter, or just a plain sidebar cutter. I would guess this one is a late 130's model or early 1940's. Mowers were used (and still are) to cut weeds along the roadway or along fence lines, but their most prominent use was in cutting hay (alfalfa, timothy, etc.) for winter use as feed for livestock. After the hay was mowed it was raked into winrows and allowed to dry for a few days, then, before it rained it was picked up and compressed into bales by a baler and transported to a barn or shed where it could be protected from the weather then fed to the livestock as needed. When I was a young boy growing up in central Ohio, I thought --and I still do-- that mowing hay was the best job in the world, especially if the mower was harnessed to an intelligent pair of mules. Mules are smarter, if properly trained, than horses. Unlike horses, mules will not founder (collapse) from hard work, over heating, and sweating. I like horses for riding, but mules are better workers. They keep up a nice steady pace to keep the blades cutting, and after having been in a certain field once or twice, you don't even have to guide them; just tie up the reins and they'll know when and in what direction to turn.
Now most farmers just hook a mower up to tractor, which is a lot quicker. But in my backward way of thinking, the pleasure of a job is not just a matter of how fast you can do it!