Here’s a garden wall that I admired recently.
These homeowners have added a 'wall' just two stones high to differentiate between a lawn area and a wooded area in their front yard.
I think it is a good solution to the problem of having to maintain a tame area around the sidewalk while keeping the woods ‘as is’. Without it, this might look like a vacant lot, tempting neighbors to sneak over at night to dump their branches, leaves, and other debris that they are too lazy to deal with properly. Yes, that happens in neighborhoods.
But with this subtle wall, you can definitely tell this is part of someone’s landscape. And, it allows the woods to be seen in its entirety without a wall or fence blocking part of it.