Hmm. . . I don't know much on Mror Holds. . . Seeing as I'm kind of a Warforged-history person, but let's see. . .
Excerpt from "Races of Eberron":
"...The dwarf clans of Mror Holds have never had the strong national identity typical of other races. As the great clans strive to unite the holdings into a secure empire based on finance, they continue to fight this legacy. The feuding dwarf clans were too weak to resist being annexed into Karrnath in the early years of the kingdom of Galifar, but turned their subjugation to good use. Karrnath's rule forced the clans to cease fighting each other, allowing them to focus on building a civilization from the tremendous mineral wealth of the Ironroot Mountains."
Sounds like your character would have a bit of knowledge on Karrnath, which if memory serves, is a country that utilizes undead. (I believe that's correct, or am I confusing countries?) Of course, that depends on the character's age, I suppose. . . Sounds, also, like you would know a bit on minerals, banking, and protection. Says, also, that twenty years ago, the Dwarves declared independence from Karrnath -- that could be something your character is proud about (Assuming Dwarf, here).
Ok, another thing: Do you know what clan your character is from? There are twelve, it seems, as indicated by the "Player's Guide to Eberron." Assuming you aren't a smaller tribe, there are a variety to choose from. I can give you a basic idea of each.
Mroranon - One of most powerful. Produces best iron ore.
Doldarun - Wealthy. Master entrepreneurs. No fueds with other clans, but no firm allies.
Droranath - Throwback to barbaric times (If your character is very old, let me know. The older history may apply to you.). Seeks to train their natural rage. Mercenaries.
Kolkarun - Shifts allegiance constantly. Opportunists. Current diplomatic ties: Aundair. Karrnath. Zilargo. Talenta halflings. Emerald Claw.
Clan Kundarak - Do you really need to know? Come on, now. . .
Laranak - Feuding with Londurak clan. Private war between the two.
(From here, there isn't too much info.)
Narathunhold - Best jewelers in world. Create ceremonial weapons.
Noldrum - Disappeared about 400 years ago! Lands believed to be haunted. . . (Interesting. Never read that bit before!)
Soldorak - Envies House K. Attempts to discredit them.
Soranath - Excellent crafters. Friends to all clans.
Toldorath and Tordanon - Longtime allies. Persuasive diplomats. Want to give Jhorash'tar orcs full clan status.
If any of those may apply to you, I can give you the full paragraph. That may help you on what you wish to know.
Keep in mind, given the map from the book, the ones on the outskirts are:
Kundarak (Northwest), Mroranon (West), Droranath (West), Noldrun (South), Soldorak (South), Tordanon (South), Narathun (Southeast). The others seem fairly well inward.
The "Campaign Setting" notes this about some Dwarves:
"To an extent, they are also feared, since dwarves are known to be ruthless in collecting unpaid debts."
Since you say you come from Mror Holds, I won't fish through "City of Stormreach" to see if I can find you anything. . . As it sounds rather irrelevant. . .
I dunno if any of that will help you, but hey, it's a start. If something perks your interest, lemme know. . . Maybe I can give you a better description, or a fuller excerpt.
-Deriaz/Bulwark
EDIT: I forgot a bit. Let's see if this helps you. Maybe not, but hey. Direct excerpt from "Races of Eberron":
"ROLEPLAYING AN EBERRON DWARF
Here are some tips and ideas to use when playing an Eberron dwarf. Feel free to incorporate any of all of these ideas into your character's personality and mannerisms.
- Never accept an initial offer, regardless of the situation (trading, bargaining with an enemy, and so forth). There's always room for negotiation.
- Keep a grim face while in public. Never reveal anything that could give anyone an advantage. When you are safely hidden with friends and family, you can let down your guard, relax, and enjoy yourself.
- Hard work and material wealth are both highly respected among dwarves. They enjoy fine things, thought they usually keep their greatest treasures hidden from outsiders. Because of this, you should be thrifty. Always look for good deals, even on things you don't need right now. Prepare for rainy days and winter. When hard times come, you will be ready for them.
- If you've got it, flaunt it. Finely crafted weapons, jewelry, clothes--showing your wealth is a way of proving the success and power of your family to the world.
- The Mror Holds are a new nation, and the dwarves are touchy about their independence. Be proud of your race and your nation, and whatever you do, don't let anyone insult your family."