Liz says to Jill during a stoppage in play.
"If your ball played from the putting green is deflected by a leaf (blown by the wind) and comes to rest on the putting green, the ball is played as it lies"      [REF: 6S1177]

Liz and David are playing as a side in a four-ball stroke round. The other side is Jill and Greg.
Both Liz and David are using are using approved caddies.
Liz plays out of a bunker to the putting green and asks Jill to mark and lift her ball (Liz’s ball) whilst she rakes the bunker. Jill does so correctly.
If Liz's caddie replaces Liz’s ball on the correct spot and Liz makes a stroke at that replaced ball, Liz will incur a 1-stroke penalty.       [REF: 5T1078]

Jill is playing stroke.
She has a long putt from off the putting green.
On her line of play is a divot hole on the fringe of the putting green.
Jill finds the divot, replaces it and flattens the surface.
Before Jill makes a stroke it is brought to her attention that her actions are not permitted.
Jill removes the placed divot leaving the original conditions for his line of play. She now plays to the putting green.
There is no penalty.        [REF: 6S1100]

David and Liz are playing stroke and David's ball is at rest on the fringe of the putting green (general area).
He has been asked by Liz to mark/lift his ball as it could interfere with Liz's next stroke. David obliges.
By accident, David replaces a different ball and removes the marker.
Before he can make a stroke, a gust of wind causes the ball to move about 60cm (2 feet) coming to rest in the general area.
David now realises he had incorrectly substituted a ball. He marks the ball's position (in it's current location) and replaces his original ball and removes the marker.
David now makes a stroke at that ball.
No penalty to David.    [REF: 6S1221]

Part of a course boundary is defined by black stakes.
By default, these stakes are not obstructions and are immovable.
The Committee may introduce a Local Rule making these stakes immovable obstructions.    [REF: 6S1230]