Mudlark

A mudlark is someone who scavenges in river mud for items of value, a term used especially to describe those who scavenged this way in London during the late 18th and 19th centuries.
Mudlarks would search the muddy shores of the River Thames at low tide for anything that could be sold; and sometimes, when occasion arose, pilfering from river traffic. By at least the late 18th century people dwelling near the river could scrape a subsistence living this way. Mudlarks were usually either youngsters aged between eight and fifteen, or the robust elderly; and though most mudlarks were male, girls and women were also scavengers.