Did the fragments come in the form of sheet metal? While not terribly common,
lead linings were sometimes used in coffins during the 19th century and
probably predate that time as well. A cemetery excavated at the Palace of the
Legion of Honor in San Francisco dating to the latter half of the 19th century
revealed several graves with such treatment. The bodies found in those graves
were reportedly "very well preserved." You can contact Miley Holman at Holman
and Associates for more info. His phone is (415) 587-8810.