Question: When I was young I went to the drive-in with my family and saw a movie; I've never been able to figure out what it was. It was about a nanny who, best as I can describe it, fed babies into a tree.

Answer: That would have been The Guardian (1990), in which a modern-day Druid (Jenny Seagrove) masquerades as a nanny so she can kidnap babies to sacrifice them to a tree spirit.