There's several theories about why they do it (stomach distress, anxiety, taste etc) but the vets I've spoken to about it all tell me its not a big deal for them to eat grass and to just live with it whatever the reason your dog is doing it.

I think it's more of a nervous habit...She isn't hungry, and I've noticed the sort of compulsive way she goes about it is similar to a smoker who has been indoors all day...

They like the tender green shoots. Sometimes they throw up, sometimes not.

They eat a grain free kibble, and other treats such as baby carrots.

Maybe give him some green beans?

but she would have some stomach problems off and on and I think the grass made her feel better.

I think she is a little thirsty... We go right inside for water but she still does it.

She doesn't throw it up (usually!).

especially the tall, fresh green grass. It doesn't cause him any distress (i.e. he doesn't barf or anything).
My vet doesn't see it as a major issue.

My current pup seems to just love the taste of the new shoots (no regurgitation).

I do keep a keen eye out for lawns that have been treated, though.

She grazed CONSTANTLY. Vet was not concerned as I don't treat my yard. She was the runt of the litter...vet thought maybe it was from being hungry a lot as a baby, just ate whatever was available. I think she was just a lab...

My hound/doberman will eat it like crazy in the spring - new shoots...he looks for them. Will pass right over older grass and only target the new ones. My boxer never eats grass.

My dogs eat food I cook that is loaded with veggies, so the vet says it's not wanting something green. My lab got green beans to supplement her food since she was always trying to lose weight. Made no impact on her grass eating habits.

Well, "eats grass" actually seems to mean she grazes and chomps on blades of grass. But she doesn't actually seem to consume those blades of grass most of the time. She's just chomping on many of them, and as we move away those blades of grass are mostly still there, just bent up a lot, and looking rather chewed-on. I do see a blade of grass in her poo every now and then, but most of the time, maybe she's trying to self-medicate with the plant alkaloids if her stomach's upset. Sometimes, especially early in the morning, there's dew on the grass and she'll get some of that.

She's got her face in the grass all the time. She's nine and healthy and doing well, even while aging a little.