There are 17 books in Phoebe and Her Unicorn Series.
Originally a web-comic called Heavenly Nostrils. The story begins when 9-year-old Phoebe Howell, a girl in the fourth grade, skips a rock across a pond and accidentally hits a unicorn in the face.
Other series related to Phoebe and Her Unicorn Series are Ozy and Millie .