To dream of a rattlesnake symbolizes your life journey and the passage of time.
New American Dream Dictionary
2. “Things” are coming apart—often emotional, sometimes in life experiences (a rattling sound of a vehicle or machine).
3. The end or “demise” of a project or situation (as in “death rattle”).
4. Feelings of having had a close call, avoided danger—often emotional, frequently a bad situation (to see or hear a rattlesnake). ... New American Dream Dictionary