Where we live, we don't have the more usual system of 'we own one boundary but our neighbours own the other'. Instead, all boundaries (i.e. fences) are 'shared ownership', meaning we are responsible for half of the cost of any repairs of the fences.
We have wooden fences close to the house but wire fences further down, which means that plants can ramble from one side to another. One of our roses, which we planted too close to the fence and which will be moved in the autumn, along with some other shrubs, is being slightly swamped by some of our neighbours' vegetables. We've agreed to extend the 'shared ownership' idea to a higher level, meaning that we get to pick anything that grows on our side. The runner beans we picked on Tuesday were delicious! In return, we gave our neighbours some cherry & almond scones. Everyone's happy.