Looking for advice on how to give exposition

So my party is currently in a part of the campaign where the story is kicking into high gear, and Im trying to figure out a way to handle exposition in a way that doesn't feel forced. I have a partial solution rn because my party is planning on finding a magic mirror in the city they just entered because of some vague prophecies from a book/bird lady(long story), but I don't want it to just be a situation of "find this mirror, get an exposition dump". I essentially want a way of expositing the lore/secrets in a way that will hook my party and make them want to know more. Any advice?

Scavenger hunt. Have them find bits of information here and there as they're looking for information on the mirror to track it down and then after they find it, how to use it. They'll likely need to visit libraries, antiques dealers, curio shops, a wizard or two, and the shady market. Seed the information they need among books, scrolls, legers, histories, gossip columns, rumors, and secrets shared for bribes. No one piece of information should tell them everything. But they should be able to piece things together based on rumors they hear about other people seeking the mirror, historic accounts of what's happened when the mirror has been used before, a dusty old book on magic artifacts that mentions something about magic mirrors and their uses, some secret information bought from a government official, and the old standby of overhearing a conversation between a butler and a maid.

This gives the players a lot of exploration and social gameplay to enjoy and at the same time avoids the problem of hitting them with one long boring info dump.

Can you give some more information? What is the story you're looking to tell? It might be easier to suggest story hooks if we know what the story is. 

One thing I find works well is tie each piece of information to a player character. Instead of just reading out lore in a big lump to the air and hoping everyone at the table pays attention try "you know X because you're a ranger" and then a few minutes later "because you're a wizard you know Y" and so on. Break it into chunks and give it to a specific person and that way they're more likely to remember at least the bit that applies to them and hopefully also some of the other bits they overhear 

When they talk to the mirror, don’t give them all of the answers. Be short and vague with what you say. Maybe even use rules like sending, only 25 words per answer. And let them only ask one question per PC. 
Sometimes, the hard part is restraining yourself from telling them everything you want to. So I try and impose limits like that to keep myself in line.

I'm a lore-loving player, but my party members are not. Here are some tips:

1) Break it up across multiple sessions. Have some sort of time-limit or usage-limit on the thing giving them the lore dump. For the magic mirror maybe it can answer 5 questions per day then they need to wait until tomorrow to ask more.

2) Have multiple ways for them to learn something / get reminded of what they learned. For instance maybe they can scry themselves to see what is happening, maybe they can learn from a book in an archive, maybe they can learn the same thing via a vision from a soothsayer, maybe they can learn the same thing from a sentient magic item, maybe they can learn the same thing from an NPC. Each one of these might give a slightly different perspective so while some information may be overlapping, there is a bit of new information each time.

As for ways to deliver exposition these are ways I have seen:

• A long lost journal or special encoded book found in loot.
• A wise all-knowing NPC seeks out the party.
• A bunch of different NPCs each with a small piece of information.
• Giving the party an object that can Scry.
• Shared vision or memory from a psionic creature.
• Vision or memory attached to an object.
• Use of History, Nature, Arcana, Religion skill checks.
• Party members deliberately seeking out information at libraries, archives, church records, or graveyards.
• Party members deliberately seeking out contacts (NPCs) that might have the information.
• Magic item that plays recorded sounds / images.
• Portal through time & space where the party can witness something first hand.
• Use of social skills in an interrogation scene.
• Private research/journals/ledger stolen from an NPC who refused to tell the party anything.
• Dreams sent by an unknown being (or a known entity)
• Eavesdropping while in a tavern / market.
• Special ritual to contact a long-dead NPC to ask them questions.
• Knowledgable NPCs accidentally rescued by the party.

Having an NPC or NPC adjacent something reveal the information would probably be better than reciting the book the party finds. That way they can interject their questions.

Quote from ereed48109 >>

Can you give some more information? What is the story you're looking to tell? It might be easier to suggest story hooks if we know what the story is. 

 My campaign is based off of classic fairy tales, and the BBEG is the leader of an evil empire who basically realized that hes a character in a storybook and now wants to gain lovecraftian powers using Mother Goose's reality warping book so that he can destroy/replace the concept of fate, but the party doesnt know that thats his motivation yet. All they know is that the Empire wants this powerful magic book and they have been moving it to a kingdom that's a part of the alliance that is fighting the Empire.

Quote from Xalthu >>

When they talk to the mirror, don’t give them all of the answers. Be short and vague with what you say. Maybe even use rules like sending, only 25 words per answer. And let them only ask one question per PC. 
Sometimes, the hard part is restraining yourself from telling them everything you want to. So I try and impose limits like that to keep myself in line.

 I had a similar idea. Since this mirror is supposed to be the mirror from Snow White(fairy tale theme and all), I was thinking the party can only ask it questions if they are in rhyme. 

Overall, thanks for the advice so far everyone! I'll try to use it to the best of my ability(especially Agilemind's thing about journals, magic items, and interrogations)!