Mood board: an arrangement of images, materials, pieces of text, etc., intended to evoke or project a particular style or concept.
To be honest, mood boards can be intimidating to me. I tend to go with the flow with home decor, picking out individual items and slapping them together.
But the truth is, mood boards can help a person (like me) visualize how everything looks together. I have found time and time again, they let me "play" until everything looks just right!