What gas smells like mown grass?

The gas that smells like mown grass is primarily associated with freshly cut grass and is due to the release of green leaf volatiles (GLVs), particularly a compound called hexenal. These compounds are released when grass is cut and contribute to the characteristic smell. Additionally, during the decomposition of organic matter, certain gases may also have similar odors, but hexenal is the most recognized for that fresh-cut grass scent.