Pancho here. Spring is busting out all over, most noticeably under our paws. The grass is definitely greener on the other side of winter, which has my human friends wondering why their dogs sometimes eat it. I've already explained why dogs eat poop. I might as well step up and appease inquiring minds for this one too.
First of all, I should let you know that I've never met another dog who hasn't tried grass at least once. It's a rite of passage, dogs-will-be-dogs sort of thing and shouldn't raise much concern, even if your dog pukes it up. Some people think dogs use it to treat their own upset stomach to induce vomiting, but there isn't substantial research to back that up.
Let me break down some of the reasons why your dog might be eating grass:
My fellow canines are pretty good at entertaining themselves throughout the day. Eating grass (and possibly vomiting afterward) are admittedly at the bottom of the list of Fun Things to Do Outside, but it's on there.
He's got intestinal issues.
A buddy of mine had an intestinal worm that interfered with his digestion. Before it was diagnosed and treated, he ate grass pretty regularly to help boost some of the natural enzymes that were not getting through.
He needs more fiber.
For the same reason you keep ordering a kale salad, some dogs are munching grass. Yeah, I'm talking about fiber (not hipster cred). My friend Petunia was a chronic grass eater until her human switched her to a high-fiber diet. She went cold turkey on the grass and hasn't touched a blade since.
He likes it.
It's pretty much that simple; some dogs like the taste of grass and they're going to graze until the cows come home. As long as you've ruled out other issues, it's not a big deal at all.
So there you have it, humans. Dogs eat grass for a variety of reasons. Don't sweat it, but do be sure to keep them away from grass that's been freshly treated with chemical pesticides. Grass won't hurt them, but chemicals will.