Cats love to nible any type of grass. Nobody knows why they do that but there are some theories. It seems to help with digestion. You can grow some yourself, you'll need a pot plant and some seeds (barley, rye, oats or wheat). For more information click on the link below:
https://m.petmd.com/cat/care/evr_ct_how-to-grow-cat-grass
When a cat chases its prey, it keeps its head level. Dogs and humans bob their heads up and down.