Hey all - I'm writing a one-shot that's all to do with memories, and I'm just looking for anything in D&D content that might touch upon it. The only thing I can find is the 'Modify Memory' spell, but obviously that's just searching via names, and not everything is going to contain the word 'memory'.

So yeah, can anyone think of anything that links to memories? Monsters created from memories, items that build illusions created from memories, maybe other campaigns that touch the same subject - anything you can think of that relates to the concept of memory in any way would be really helpful.

A Wizard, and only a Wizard unless they are a Bard, Cleric, Druid, Sorcerer, or Warlock, can use Magic Initiate feat to cast the Encode Thoughts cantrip.  This allows them to take one of their memories and turn it into a semi-tangible item called a "Thought Strand".  that they can carry around.  If they are concentrating on Modify Memory during the minute they are casting the cantrip they can pull the modified memory from someone else instead, and then they will need to cast Detect Thoughts in order to read the modified memory.

The Telepathy feat allows anyone to cast Detect Thoughts once per day, so telepaths could share it around, and Kalashtar are telepathic.

The only other thing I could find, and I doubt this would be all that helpful, is you could use Speak with Dead and ask the corpse about what it remembered in life. 

Unfortunately, the spell only lasts for 10 minutes, and:

You grant the semblance of life and intelligence to a corpse of your choice within range, allowing it to answer the questions you pose. The corpse must still have a mouth and can't be undead. The spell fails if the corpse was the target of this spell within the last 10 days.

Until the spell ends, you can ask the corpse up to five questions. The corpse knows only what it knew in life, including the languages it knew. Answers are usually brief, cryptic, or repetitive, and the corpse is under no compulsion to offer a truthful answer if you are hostile to it or it recognizes you as an enemy. This spell doesn't return the creature's soul to its body, only its animating spirit. Thus, the corpse can't learn new information, doesn't comprehend anything that has happened since it died, and can't speculate about future events.

So the only way this would work is if the corpse was 10 days old or less, you and your party had nothing to do with it's becoming a corpse in the first place, and you'd have to ask nicely.

Lore wise, the Ravenqueen collects memories contained within trinkets, mostly, sometimes larger structures.  I'm actually building a one shot sort of "memory heist" right now.  I don't think there's a lot of mechanics to explain how the Ravenqueen does this (she's sorta a minor god).

Hydroloth are yugoloth who are hired to steal peoples memories and return them to their master.

Amnizus have a lot of powers that relate to memories. 

Greek mythology is filled with things that have to do with memory.  One of the deities is Mnemosyne, the goddess of Memory.  She is the mother of the nine Muses, who inspired artists and historians.  She was said to be the guardian of a pool that had an effect similar to the waters of the River Lethe, which erased the memories of souls in the afterlife.  Zeus, the king of the Greek Gods was her nephew.  She was one of the original Titans.  That was who Zeus Almighty slept with, he's the father of those nine Muses.  Greek myth is kind of icky when it comes to interpersonal relationships, and Zeus is one of the worst offenders.

In chapter 2 of the Dungeon Master's Guide, it describes the various planes and how player characters might travel to them.  They are all sorted out by Alignment.  The Good souls go to the Upper Planes and those who were Evil go to the Lower ones. The True Neutral ones go to the Outlands.  That gives you 17 places characters might adventure, and all of them filled with inhabitants to interact with.  Some can be summoned to the mortal planes, the specific one being the campaign setting, such as the Forgotten Realms.

In the tragic story of Orpheus, Euterpe, the Muse of Music must have inspired him with the idea to seek out the shade of his promised bride, Euridice, and so Orpheus traveled to the domain of Hades, the Lord of the Dead, who keeps all the souls until he has judged their proper destination.  It was the music Orpheus played that softened the heart of Hades himself and made the Furies themselves weep, and he gave Orpheus permission to take Euridice back to the mortal realm.  Hades only asked for one thing.  Orpheus would have to show some faith.  He could not look behind him to see if Euridice was following him.  He would have to place is trust in Hades.  Naturally, Orpheus failed and did exactly that.  He looked back, and he had just time enough to see his wife's look of horror as she was yanked back into the domain of Hades.

Each culture had myths and legends about where the souls of the dead went.  Spirits were undying and kept being reincarnated, they would turn up in whatever equivalent of the Feywild that culture had.  Souls would travel to any of the 17 planes in the DMG.  All the information you could ever want can be found on Wikipedia or similar places if you need further inspiration, that would be the domain of Clio, the muse of History.

Aboleths, Mind Flayers, etc...

I am a super new DM, and still building my campaign, but because I have 6 people that are playing. I needed a way to make is so that we could have a game night, where we can play without having everyone there, and a way to give players a chance to replay the parts they miss. So…. I created an NPC for that purpose. He is an Elderin Elf Bard with a Mysterious past, and a large white “back” pack. The pack allows players to replay their own memories, or we can do side quests using the Bards past experiences. It takes the time element out for spells, because it’s played out in the mind, and the pack has creation magic, that allows players to keep certain items or resources that the players find on those side quests. It took a lot of thought, but it seemed the best way to let players see what “would’ve happened” if they made different choices, and allow the group to continue to play even if some people can’t make it to game night.

@Unchecked_door Would you be willing to share the stats/some details for this item? This is the exact situation I find myself in at present! I wanted something fun that could help get the players more involved in their characters' backstories and RP as well as keep them involved even when they can't be at sessions. I was wondering where to begin with an item that could induce someone's memory for them to relive. Sorry, I know I'm a few years late on this thread lol!