It can come from a lot of places.
This is my mood board. It changes subtly every so often and is a carefully curated mixture of beautiful postcards of people's work I am drawn to, pictures of my own work, biz and postcards of friend's work who I find particular great, trinkets, things Adele made me when she was little, comics, Gareth's tag from his little hospital bed proudly stating, "I'm a boy!" and photos.
It is so tidy in these photos. I have since added, subtracted, and gotten a little sloppy with overlapping additions.