The Crushed Spider Egg artifact can be found in Tirith Mesas, in the south-western part of Sea of Núrnen.
Crushed giant Spider egg shell, Third Age, circa 2938
"This Ungol egg has clearly been kept as a memento, but for what reason? Does it represent yet another casualty in the burgeoning war in Mordor, the one being fought between the forces of Sauron and the children of Queen Shelob? Or is this just a remnant of some Uruk's supper?"
"I speak with the Mouth of Sauron, the second Dark Lord of this Middle-earth. Our will is his will. Mordor is ours, and fairly won. You will take this message from Sauron back to your spider Queen Shelob, the last daughter of Ungoliant.
Your eggs will not be allowed to hatch in Mordor. Your children will no longer prey on the Morgai Flies. You will depart this realm, abandon your nests in Nan Ungol.
You have grown fat on our generosity. We have fed you as we would a pet, allowed you to run unfettered. This ends now. Our union, as it was, has ended. Our will is irresistible. We have spoken."