We have two sister golden retrievers, Marzipan and Penguin who are around 9 years old. We'll often see both of them grazing around our gardens eating grass, dandelion buds (i pick the small tender ones deep in the leaves for them), dandelion flowers, wild strawberries and who knows what else.
As far as veggies and fruit, we do try to feed them veggies of some sort with their kibble, or add some whole foods such as baked potato or rice and give less kibble. They would do anything for baked sweet potato. They LOVE fresh veg and berries picked from the garden right in front of them. They sure are hound dogs! Favourites are asparagus and peas, strawberries, they will take a sour sorel leaf but politely spit it out haha, blueberries, raspberries, haskap, they probably eat better than us. They get a daily chunk of apple, maybe some orange or melon. In winter, i chop up carrots and other root veg, they love cabbage (stinky poot poots!), tomato, peppers. I suppose I could have just said they love it all!
One thing i've started giving them is a piece of dried nori (toasted seaweed) every day and they absolutely love that gross fishy taste.