One of my favorite things to do with any game is to collect game aids, and for the Digimon Card Game that means deck-specific memory tokens. Luckily there are a lot of Digimon trinkets that would work well for this purpose.
First off are small digimon toys. My wife already had a lot of these, and I've bought a couple more for thematic matches.
» Tyrannomon: As the poster-monster for my Taiga Tyrannomon deck, I had to have one of these.
» DemiVeemon: I also have a Veemon model, but I like to use my deck's Level 2 when they're available. This one's obviously for Vee Jamming.
» Koromon: As with DemiVeemon, this digimon is the L2 for its deck - Shine Yellow Tamer Party.
» Upamon: Another L2, this time for Yellow Pillowfight.
» Lalamon: For Green Digi-Burst I originally wanted Yokomon, but that toy is more expensive than I'd like to commit to. Luckily we had a Lalamon toy, and that's a relatively prominent Rookie in this deck.
» Kuramon: This one's a Baby (Level 1) digimon, so it's not actually represented by a card, but it's part of the Diaboromon line and therefore great for Diaboromon.dec.
» Gigimon: is the Level 2 for my Purple Rookies deck. I had to repair this model because the tail was damaged, so this one is mostly hand-painted.
» Holy Ring: My wife has had a necklace with a Holy Ring on it for a long time; it's the first thing that occurred to us to use as a Memory Token. It works really well for Yellow decks.
» Tamer's Evolution Box Marker: The Tamer's Evolution Box contained a Memory track and a small acrylic marker to use with it.
» Acrylic Digivices: I got these markers on Etsy. There's a Digivice from the 2020 reboot, which seemed apropriate since that's where most tamer art comes from in the game; I got myself a red D-3 because that matches Hawkmon which is my favorite, and for my wife I got a blue D-Power because it's the one that matches her favorite, Renamon. She's also a fan of Season 7 (Appli Monsters) so I got an App Drive token too.
» Dice: The Digimon Card Game doesn't actually use dice, but I like them for deciding first player. I got two blue ones with the Blue Card symbol, plus a yellow one with a taijitu (a reference to Renamon) for my wife.