Our Sophie is a ground Hoover; she'll eat anything she finds. We do not have a fenced in yard, so she is always on a leash when she goes out. IF we had a fenced in yard, I would not be able to put her out there. The constant diarrhea from her backyard buffet would not be welcome. I take Sophie on long walks, one to three miles, and that way she and I both get our exercise.
I have a friend whose little poodle keeps eating the mushrooms that randomly grow in their back yard. They cause the dog to hallucinate! My friend has given up in trying to eradicate the mushrooms and keep her dog from eating them. She doesn't let her out into the yard often, if she can help it. They have lived in that house for 25 years and their previous poodle never ate anything out there. Back yards can be really scary places for dogs.