I sat in on a free lecture by Bethanne Nemish and she talked about how she does exactly as you describe. Not only for colors but for shapes, motifs and design inspiration. Her award winning quilt "October Sky" had a wonderful arched FG peicing incorporated into the design along the top of the quilt that she took inspiration from a photo she had in her notebook. She says she gets them from all over. Some she takes herself, she tears pages out of magazines, all kinds of source for her notebook. You can see pictures of her quilts here:
https://www.whitearborquilting.com/portfolio/