Happy birthday, Ava Phillippe! The daughter of Reese Witherspoon and Ryan Phillippe is celebrating her 20th birthday today! In honor of Ava's birthday, the Oscar winner took to Instagram to share a sweet tribute to the college student, writing, "Watching your little girl grow into a gorgeous, thoughtful, compassionate, fun-loving young woman defies words. It has got to be the greatest gift I could ever receive. I love you @avaphillippe to the moon, around the stars and back! Happy 20th!" In response, Ava commented on the post, "love you so much, mama." Along with the message, Reese also shared an adorable throwback photo of a young Ava smiling for the camera with a red bow in her...