Conversation so far:
Where was Ralph Waldo Emerson born?
Ralph Waldo Emerson was born in Boston, Massachusetts.
Who were Ralph Waldo Emerson's parents?
Ralph Waldo Emerson was born in Boston, Massachusetts, on May 25, 1803, a son of Ruth Haskins and the Rev. William Emerson, a Unitarian minister.

Question: Who was his mother?
Self-contained rewrite: Who was Ralph Waldo Emerson's mother?