1- What If... by Samantha Berger. This is such a special book that would make a wonderful gift for any child with a creative spark or vivid imagination (hopefully, every child! : ) The verse progresses through different ways the main character could express her imaginings and tell her stories, even in the absence of dedicated resources. ("Without any floor / I could still use the land / and sketch out a tale / in the dirt with my hand.") It has a wonderful universal message about the resilience (and importance) of our creative spirits, and the mixed media illustrations by Mike Curato feel really grounded in a kid's life and interests and really magical all at the same time, incorporating photos of everyday objects treasured by children, like flower petals, leaves, and little jewels. Fun fact: the author was inspired to write this book after having to quickly evacuate her flooded apartment in the midst of an ongoing creative project. She had to leave most of her belongings behind, and ended up creating similar found object and leaf collages to the one photographed for the book while she was away.
You could pair this book with any manner of age-appropriate art or craft supplies (the whole point of the story is that it's possible to tell a story with almost anything) - in addition to these items, which looked pretty with the book's coloring and are more traditional art supplies, you could consider origami paper, a shadow puppetry gift, rhinestones, sunprint paper, a flower press, seeds, or musical instruments (all are means of self expression included in or related to the story.)
2- Washi tape - There's tons of it out there, I liked the sparkles and coordinating colors in this set
3 - Sketchbook
4 - Watercolor brush pens - these are so fun, they can be blended with water right after use for a true watercolor look that's much easier and less messy than a traditional set of the paints.