Here is the full list of all 21 Grass Cutter trophies - there are 4 bronze, 8 silver, 8 gold and 1 platinum.
Eliminate multiple monsters in less than 1 second
Use a bomb
Eliminate robot
Make the first purchase
Eliminate quadcopter
Get wet in the rain
Gather up energy when there is less than 5% left
Take a mud bath 20 times
Scare the birds 50 times
Cut 1000 squares with grass
Immerse the first box
Complete the first level
Good job! Completed all tasks!
Scare the cats 15 times
Scare the dogs 20 times
Disable 50 monsters
Dive into the water 20 times
Drive by 10 times on the sand
25 times, purchase 15% of the energy
Face the monsters 50 times
Break 100 barriers