I am currently reading Underground London, by Stephen Smith. It mentions toshers, who used to go down into London sewers to hunt for any valuable objects that might have been lost and washed away. Not the most glittering of careers, but it has left us an expression, "a load of tosh", which means "a load of nonsense", tosh meaning here rubbish, twaddle. Funnily enough though, originally tosh was the word used by toshers to designate the treasures they found in the sewers, as this quote found in the Oxford English Dictionary tells us:

The sewers-hunters were formerly , and indeed are still, called by the name of "toshers", the artiches which they pick up in the course of their wanderings along shore being known among themselves as "tosh", a word more particularly applied by them to anything made of copper. (H. Mayhew, 1852)