Here are some clay pipe bowls I found by eye on the Thames foreshore recently (I can't dig or scrape the foreshore without a permit).
I've discovered by reading the history of pipes that as tobacco became cheaper the pipe bowls became larger which is a helpful way to date them. The oldest pipe bowl in the photo is the smallest one probably mid to late 17th century judging by the pipe dating chart I found online. I'm no expert though so please correct me if I'm wrong.
The little buff coloured cube in the photo below is a ceramic 'knuckle' or spog. They were used in a child's game when one would be thrown up and the child would pick up as many as they could while it was in the air....19th/20th century (Thanks London Mudlark for confirming that). Sounds very much like the game of 'Jacks' that I played as a kid at school.
I also discovered yesterday that pieces of pottery are called 'sherds' (whereas pieces of glass are called 'shards)'.
I never knew that!
I quite enjoy looking up the designs & attempting to date them. Even though they might only be a very small fragment of history it's still fascinating. If you look very carefully you may see a tiny butterfly on one of the 'sherds' at the bottom.