When I was a boy in the UK we used to pick wild blackberries and several other types of berries and eat them. No problems. Mind you, we also used to steal fruit from people's fruit trees. Maybe these apples, pears, plums, damsons and the like tasted even better because of the risk factor involved.
As a child (World War Two years) in England, I don't think I ever tasted a piece of fruit that was not either taken from the wild, or pinched from someone else's garden or a farmer's plot. We even brought home carrots and potatoes purloined from nearby fields. And the chastisement we got was really, tongue in cheek, for we were well aware how needed such added household food supplies were.