The other day we were standing around in the garden of some friends and we noticed a pile of flint flakes. We didn't think they had just unearthed a hitherto unknown flint working site, although that is just what it looked like. I thought they must have accidently hit or dropped a flint nodule that was just lying around in the garden and it had shattered.
The real story was somewhat more interesting than just an accident though. They explained that last time local archaeologist and expert flint knapper Bertrand Walter had been giving a demonstration the heavens had opened and the demostration was hastily abandoned in a rush to get indoors. Our friends knew that Bertrand is very careful to clear away any trace of his demonstrations after they are concluded. So once the rain stopped they went in to the museum grounds and picked up all the pieces, removing them to their garden.
The reason Bertrand is so meticulous about clearing up is mainly because he is worried that unscrupulous people will pass the flint off as genuine prehistoric pieces, but also because flint shards are sharp and could injure someone.