The flower pots were used by Alex Pruitt as one of his traps in Home Alone 3.
Home Alone 3
When Alice Ribbons tries to enter the house via the back gate she finds it locked. She climbs over the gate and lands knee deep in mud. She loses her balance and falls onto her knees which triggers a cord which causes a flower pot to fall from the roof. It hits her on the head and knocks her out.
After she comes around, she makes her way through the sticky mud, but loses her balance and falls backwards into the mud. She triggers another cord which causes another flower pot to fall on her.