Cemetery maps usually show the burial grounds of people who died in the late 1800s and onward. For older plots, contact the caretaker to see if she has other records that may help locate them.
Additional records that might help pinpoint a specific grave include death certificates, obituaries and funeral home documents. Public libraries often possess resources that give insightful information on burials. Some websites, such as those that trace family history, can also provide details regarding an ancestor's final resting place. Lower-class people who were buried prior to the 19th century typically do not have inscribed stones, so it may take extra effort to find them.