The night after returning from the Traders, in Carvahall, Eragon tests the hollowness of the "stone" as Merlock showed him, and finds out that it is, indeed, hollow. As he sleeps, the stone begins to wobble around, sharp cracks zigzagging through the surface. Eragon is woken by the stone, curious, and watches the stone until it finally shatters. In the stone's place is a blue baby dragon, revealing that it was not a stone, but an egg.
Eragon recoiled in shock. Standing front of him, licking off the membrane that encased it, was a dragon.— Final words of Fate's Gift