Do any unique items spawn in (upgraded) houses?

You can spend a lot of money upgrading your house(s) in Skyrim, which will eventually include things like food, potions and ingredients spawning in the house (one-off or respawning, I'm still not sure, but that's a different question!).

Are there any unique items that are only obtainable from upgrading a house (either fully or partially)? I think I read something about a Stone of Berenziah spawning in an upgraded house but I can't find a source for that. Perhaps some weapon or armour gets added to a display stand?

Solution 1:

One of the 25 Stones of Berenziah is in Proudspire Manor, but this does not require any upgrades.

There are no unique items for upgrading any house, however.

Solution 2:

You are right you can get Stone of Berenziah from upgrading one of the houses (proudspire manor). No unique weapons/items are found as far as I can tell from experience.

source - my experiance and http://elderscrolls.wikia.com/wiki/Stones_of_Barenziah