Thank you, in advance!
Update: Thanks to Amelia and Alison! It is Pieris japonica, or also known as the lily-of-the-valley shrub! Looks like lily-of-the-valley, but it is a shrub. It has to be easy to grow because it is growing like a weed outside my window and I've neglected to water it... umm, ever. It was here before we moved into the house.