Samphire Hoe Flints
Samphire Hoe is an area of artificial land created using the Channel Tunnel spoil material - and, of course, the nearby beaches. The cliffs are huge here and there are a whole range of different stones to be found, including ones that are fresh out of the cliffs and those that have been in the sea for a long long time. The freshness' of some of them means that you can find structures here that would not survive for long once the stone ends up in the sea. There are many fossil sponges here, leading to hagstones and other unusual structures. Also, other fossils and pyrite nodules coming out of the chalk.
The artificial nature of the Hoe itself raises the intriguing possibility of weather any of the stones here might have been dug up from the channel tunnel works. It's hard to say! Probably fanciful, given that they could so easily have come out of the cliffs somewhere around Kent, but I can dream!