But seriously, not a bad thought neogreggory, and seeing as the trolls don't exactly have much interest in making, using, or owning small pieces of technology, pretty baubles excepted, they'll be trading their strength and size. 

Feel I should clarify what the troll-spawn are: humanoid troll-spawn are generally slightly taller and stronger than your average human, with mottled, calloused skin, often a grey colour, very little hair, and long limbs. They can breed among themselves and with other races, though they usually breed true to their parent race; human troll-spawn give birth to humans. That said, they have a fairly low fertility. They might then hibernate their child with a troll for a few years to protect him; troll-spawn have a very low infant mortality rate. While generally resistant to disease, they can be prone to physical or mental deterioration relatively early in life. So their population is pretty much tied to the number of stone-trolls in the world.