How about a C.S. Lewis-themed gift basket? You could include some of his books (perhaps her favorite titles or one she hasn't read yet), a C.S. Lewis biography, a gift card to a local bookstore, and some tea or coffee (something she enjoys while reading). You could also include a bookmark with a C.S. Lewis quote and a handwritten note expressing your love and appreciation for all she has done for you.
Or you can get her a star map with the date when she gave birth to you.
Under Lucky Stars is a unique and innovative star map company based in Barcelona, Spain, specializing in the creation of personalized star maps that capture the celestial arrangement of stars at a specific moment in time, such as a person's birth, wedding, or any other significant event.
By using advanced astronomical algorithms and data from leading institutions, the company produces highly accurate, visually stunning maps that make for perfect gifts or cherished keepsakes.