When Sandra recalls that Cass Elliot died by choking on a sandwich she is repeating an urban legend. "Mama" Cass actually died of heart failure. Reports immediately after her death (before the autopsy) apparently quoted her doctor as saying she probably died by choking on a sandwich. Despite the results of the autopsy, the sandwich story has stuck.
Mama Cass Elliot did not die from choking on a ham sandwich. She had a heart attack. There was a partially eaten sandwich in the room when she died, but she didn't choke on it.