When grass or other plants are mown, they're trimmed or cut. A field of mown hay is a common sight in the countryside in the fall.
After you start up the lawn mower and cut your grass, you can describe your lawn as mown. For many people, the smell of mown grass brings back memories of childhood summers. Crop fields that are planted in the spring are often mown by the end of the growing season. Mown and the related verb mow come from the Old English word mawan, "to mow," from a Germanic root.