The first two, those she had revealed without hesitation, were both smells of death, ultimately. Constructive death ('redemptive' death would be too strong a term for such minor matters—or would it?), but death nonetheless. If Hermione had to describe the aroma of freshly-mown grass, she would have replied that it smelt of life and greenness and sunshine and youth and something akin to hope. For once, Hermione's instinct overrode her intellect to a small degree (for it is only grass, after all), and ignored that grass died to bring about her favorite scent. Those grass cuttings would decompose and nourish the grass from which they came, and more grass would grow and be cut and die and so on for ever.
Hogwarts was surrounded by verdant fields. But Hermione insisted that magical techniques for cutting grass produced an inferior aroma to Muggle methods. She thinks back to happy days from her childhood, when she sat under a tree reading and her father struggled to mow their lawn with his battered machine. Sometimes her mother would bring out lemon squash for her two beloved laborers and the three of them would sit together, her mother and father chatting quietly while Hermione continued to read (no one could pry books from her hands back then, either.) Once she went to Hogwarts, these scenes stopped, for no particular reason she could discern. She now preferred to read inside, and she was too fascinated with the spectacles of her new magical world to notice more mundane pleasures, like the scent of mown grass. During her first few months at Hogwarts, when she was bitterly lonely, she did dwell on those memories, even though they were Muggle pleasures and she was so eager to be accepted by her magical peers. But once she had made friends with Harry and Ron, she ceased to think much about those days. In fact, it wasn't until she smelt the Amortentia in her sixth year that she realized that those experiences were still important to her. Despite championing Muggles in the abstract throughout her days at Hogwarts, she did not think much anymore about her own particular Muggle experiences. She spent less and less time at home, even during the holidays. After all, Harry needed her. It was only grass.