I am a younger member of the administrative team and my writing is often corrected by an older gentleman who puts that extra comma after the second word in a list of three. Just wanted to make sure I was correct about what I was taught in college and what speech actually sounds like.

Which is correct:
She bought apples, oranges and pears.
OR
she bought apples, oranges, and pears.
I was taught in college that the first one is correct and matches speech patterns.