Dog eats grass and throws up

My dog has been eating grass then throwing up about five times a week now. This occurs normally in the morning hours. She eats three one-cup servings of dry food a day, spaced out over the entire day. She eats well and is otherwise healthy. Any suggestions?

She does this on a daily basis? She may be allergic to something in the kibble thats upsetting her tummy.

My vet said the same thing, then retracted when I told him she has been eating the same food for five years. She only does it in the morning hours... and I tried spacing out her eating time but it did not help. It's almost like she eats the grass and IMMEDIATELY throws up... then is fine for the day! I have already consulted my vet but he did not have any advice other than spacing her eating hours and that didn't work. Any suggestions?