Where to sell stolen items?

[Timmy the Dragonborn]

?

[Pim]

You have to take the ring from the dead person near the Executioner's house, and go to the miller that saved you. He'll tell you to go to another miller, give him the ring, and now you can sell stolen goods to both millers

[swift]

Just sell them to traders, but be careful of who or where you sell them.

[Kommissar K]

At a fence? Where are you in the game? In the prologue, there is a woman named Marta near the Talmberg tavern that will buy stolen items.

After that, once you get to Rattay, work for the miller for a bit, and he'll direct you another miller slightly north of Rattay who is also a full fence and buys stolen items.