There have been several mystery series featuring mothers, although most of them are (a) cozies and (b) involve single mothers. If your mother might enjoy a Mom protagonist for Mother's Day, even if Mom doesn't happen to be an amateur sleuth on the side, here's a selected list. No doubt there are many more, and if you know of others, please chime in...
- Jennifer Apodaca -- Protagonist Samantha Shaw runs the Heart Mates Dating Service while raising two boys and keeping track of her ornery magician grandfather
- Jo Bannister -- Single mother Brodie Ferrell starts her own search service, "Looking for Something?" in Dimmock, England
- Lauren Berenson -- Melanie Travis is a special education teacher, divorced mother, and new owner of a standard poodle
- Jill Churchill -- Jane Jeffry, a Chicago housewife and single mother
- Diane Mott Davidson -- Goldy Bear series, featuring a caterer and single mother in Colorado
- Joan Hess -- Claire Malloy, bookstore owner and single mother
- Jonnie Jacobs -- Kate Austen a recently-divorced young northern California mom
- Faye Kellerman -- L.A. homicide detective Peter Decker and his wife Rina Lazarus, mother of a troubled teenage son
- Leslie Meier -- Lucy Stone, a Maine three-time mother and part-time mail-order business employee
- Anthony Oliver: Lizzie Thomas, Welsh mother-in-law in an English village who solves crimes with the help of retired Inspector Webber
- Elizabeth Peters -- Amelia Peabody, Victorian Egyptologist and mother of Walter, also known as Ramses
- Phil Rickman -- Merrily Watkins, single mom and Anglican priest
- Sara Rosett -- Writes the cozy Mom Zone mystery series
- Alexander McCall Smith -- Precious Ramotswe, #1 Ladies Detective Agency, mother to two adopted orphans
- Ayelet Waldman -- Juliet Applebaum, "mommy-track" mysteries
- Valerie Wolzien -- Josie Pigeon, single mother, carpenter, and owner of a contracting company
If granny gumshoes are more your thing, this link has some suggestions. There are also a few mysteries themed around Mother's Day:
- Mignon F. Ballard - Angel at Troublesome Creek
- Dorothy Cannell - How to Murder your Mother-in-Law
- Wensley Clarkson - Mother's Day Murder
- Nancy Fairbanks - Bon Bon Voyage (Culinary Msytery with Recipes)
- Jane Haddam - Murder Superior
- Lee Harris - The Mother's Day Murder (Not-To-Miss Series)
- Patricia MacDonald - Mother's Day
- Dennis McDougal - Mother's Day
- Nancy Pickard (Editor) - Mom, Apple Pie & Murder: A Collection of New Mysteries for Mother's Day
- Joshua Quittner, Michelle Slatalla - Mother's Day
Take a couple of books, throw in some flowers and chocolate, and you'll make your Mum one happy lady, just like my own mother, a self-proclaimed chocoloholic and mystery addict. Must be in the genes.