I'll lay it out for you: the best gift for a nostalgic mom is a book full of pretty pictures. You could make a photographic family tree, including as many generations as possible. You could document your mom's life and leave blank areas where she can write down her memories. You could make a brag book of you and your siblings, of your wedding or of that new grandbaby. It doesn't matter. She'll love it. $45 at Pinhole Press.
I'm also loving this family tree necklace, with initialed leaves dangling from a branch. $59 from Etsy.
For the nostalgic, pack-rat mom, appeal to her love of the past and that pesky desire to keep everything. The Container Store stocks cute organizing accessories, like the colorful boxes and striped basket above. If your mom has slightly anti-technology tendencies like mine, personalized monogrammed stationary from Rifle Design might be just the ticket. Lipstick Queen's Medieval Red is the perfect shade for everyone and surprisingly moisturizing.
Your mom probably cherishes her own mom, so pick up one of Anthropologie's charms to add to her heirloom bracelet (or start one of her own!) and a bottle of her mom's perfume. My NaNa wore Lancome's Tresor. Finally, what mom doesn't love a pretty scarf? Madewell's pattern is affordable and just bright enough to add a little pep to her neutral sweaters.