can you be vegetarian in the wild? where would be good places for this?

In theory it would be possible depending on where "the wild" is. You have to remember that the Earth is full of diverse climate regions and, as a result, there are many areas where vegetation grows seasonally or even to the point where edible vegetation (edible by humans that is) is extremely rare and insufficient to support life. In these regions the hunter/gatherer part is almost fully meat and meat related products.

It would be difficult to obtain all of the necessary nutrients for life in many of these regions without meat which is why you find that the vast majority of indigenous people consume meat as a part of their diet. When you consider how close they live to the land and their knowledge of the food types provided it goes to show that the vegan lifestyle is a modern invention and even the vegetarian lifestyle may not be sustainable without some modern production methods.

Watch the movie "Into the Wild". It's the true story of a young man about 23yrs old, who left everything to hike his way to Alaska. He was living by gathering AND hunting and he died of eating a toxic plant which caused him to starve, and the reason he ate THAT plant was because there was nothing else. He was all educated on what to eat etc. but mistakes can still be made. This movie is a tear jerker.

There is no hunter gatherer society without game. It takes 2000 calories a day to sustain a person. Hard to find in nuts, fruit, berries, seeds and roots alone. In the past the men hunted to bring in the big food and the women did their thing gathering. The two together made life sustainable. You need both to survive in the wild- this is why our ancestors made us possible.

Grow food in your backyard!

No. As omnivores we can't live on plants alone.