I recently finished the thieves guild quests but realised I hadn't found 3 of the larceny items for Delvin. I decided to go out, get the 3 items and then bring them all back. This didn't work, when I found and picked up the third item it 'completed' the quests for the 3 items 'return item to Delvin'. This has left the 3 items in my inventory, he wont speak to me about the items and I wish to sell them to him so they appear in the thieves guild.