This dates back to pre-domestication when dogs would eat all of the their prey, after a kill. This includes eating the stomach content which would commonly be greens, vegetables and berries.
Dogs today, still eat wild berries, plants and vegetables as well as other plant material. This is not uncommon, as your dog will still have those cravings.
Sometimes dogs will consume small amounts of grass or other plant material just because they are hungry or for the taste. Eating large amounts of grass can be because your dog knows that the tickle in their throat or stomach lining will cause them to vomit, relieving them from the discomfort of stomach gases or other stomach issues.
You should not be concerned if your dog is eating small amounts of grass, but it is always a good idea to follow up with your veterinarian to assure that your dog doesn’t have any underlying stomach issues.
Dogs will sometimes re-eat the grass filled vomit they just produced, so make sure you haven’t just eaten if your going to watch that happen … Gross! Remember … 10 minutes later, your dog will be giving you kisses with that same mouth … LOL … Don’t deny it … you know you do!