From Destinypedia, the Destiny wiki
Location:
Fields of Glass
Rarity class:
Uncommon
Loot drop:
Yes
Source:
Patrol Fields of Glass, Mercury
Simulation Seeds are a planetary material that can be harvested in the Fields of Glass on Mercury. They are apparently matter that forms the simulated realities in the Infinite Forest.
Simulation Seeds can be redeemed for reputation with Brother Vance.