Answer
Much of this answer is dependent on where you live and what the general rules are where you live. Some wilderness/natural land is not prepared in such a way to be mowed and should in my opinion be kept as natural as possible. However, when moving into a Homeowner's Association you probably signed what is called a "covenant," stipulating how your property should be kept. In this case, I would say the John Deere is dear to God that you should mow your yard. After all, even Adam was placed in a perfect garden (Gen. 1:31) and demanded to maintain it (Gen. 2:15).
As Paul writes in 1 Corinthians 10:31, "So whether you eat or drink or whatever you do, do it all for the glory of God." Everyday things matter to God even our yards, homes, and driving.
I remember one morning at about 6:00 AM when I was driving to seminary. One of my seminary professors passed me on the road. He was speeding, but not really going all that fast. However, he knew I was a former police detective and felt very bad. My professor confessed his sin before the whole class. It dawned on him that someone - THE LAW - was watching.
However, the fact is that Someone is always watching and it is to him we are to bring glory. In addition, we are supposed to obey the rules of man when they do not conflict with biblical revelation (Rom. 13:1-7). Maybe driving fast does not seem all that bad. However, when you realize that individuals are hurt, maimed, and even die in accidents, reality should begin to set in thou shalt not kill. You may not realize this but some fatal accidents could be prevented if the offending party was only going one mile per hour slower. Speed matters! One mile per hour seems like such a small thing, but in reality it is a relationship thing, and it really matters. While these things should not put us into bondage to a list of a bunch of dos and don'ts, they should be in us a living opportunity to show how we love and appreciate what God has created.
We never know who is watching and we never know what another is thinking. While most speeding does not end in fatalities or even accidents, the atheist driving down the street sees a vehicle with an ichthus (fish) symbol speeding and says to himself, "There goes another Christians who says he cares for people and yet is endangering them! On the one hand, they preach they care, and on the other they show that they really don't. They are just a bunch of hypocrites." Again, these small things matter.
While we cannot control what others think, we can glorify God in all things. Maybe our glorifying God will help stop their stinking thinking? Even if it doesn't, you will still have nicer yard and be a much safer driver. More importantly, though, you're beginning to maintain a disciplined life of bringing glory to God in all things.