Summer-autumn grass.
Time frames: second half of summer - first half of autumn (depends on the region).

The scene contains models of grass and flowers, a 6x6 m meadow with tuned corona scatter for 4 types of vegetation.
collection grass - https://3dsky.org/collection/shared/5081805 
Corona scatter is missing in FBX file. They can be configured using screenshots in the archive;
The archive files 3ds Max 2011 (corona) + FBX.