"100 books hand-selected by our editors that we think [Mom's will] enjoy"
Dear Mom, bought you a 99c ebook. Enjoy.
100 Books for Mother's Day reveals that Amazon thinks Mom's enjoyment is limited to a swathe of pastel pink and turquoise books about motherhood, romance, being (a certain kind of) women, and family dramas with a literary twist... and a few rather out of place looking paranormal fantasy or historical memoirs thrown in.
I would suggest giving your mom a book you like, or she personally might like, or a voucher so she can chose her own damn book.