Hide or keep pebbles.

Northampton Rocks is the name of a group who paint images on pebbles with the main purpose of leaving them for others to find.
On the back of each one is a message: keep or rehide, f/b Northampton Rocks.
Its interesting how far some travel and of course kids and adults think it's great fun!
These have been left on our doorstep by our daughter it's a real treat when we find a new one!