When he first enters the dragon's lair, he returns with a two handed cup.
The One Ring... Which left Frodo in an unfortunate situation later on.
a two handed cup...
money, his hat, and his handkerchief
On page 85 of 'The Hobbit' Bilbo asks "What have I got in my pocket?"
Bilbo finds the ring that he later finds out belongs to Gollum who lost it. Gollum riddles with him in order to eat him, after bilbo asks him what is in his pocket he gets it after he helped bilbo get out of the mountain.
During the riddle game, Gollum’s ring is in Bilbo’s pocket.
Bilbo asks Gollum "What's in my pocket" (the Ring) and Gollum cannot answer.
That was the big mistake Bilbo made. There was no one to put him in it and close it up for him.
The Arkenstone of Thrain.
Bilbo finds the ring on the bank of the lake where Gollum lives, and put it in his pocket. While thinking about it he says to himself 'What have I got in my pocket?', which Gollum takes as a real question and he cannot answer it.
On page 85 of 'The Hobbit' Bilbo asks "What have I got in my pocket?"
Bilbo finds the ring that he later finds out belongs to Gollum who lost it. Gollum riddles with him in order to eat him, after bilbo asks him what is in his pocket he gets it after he helped bilbo get out of the mountain.
During the riddle game, Gollum’s ring is in Bilbo’s pocket.
Bilbo finds himself in a cave after escaping the goblins. The cave is home to a creature who calls himself gollum. Gollum is in a mood because he has lost his precious(the ring in bilbo's pocket). Gollum challenges Bilbo to a riddles contest, if Bilbo loses Gollum gets to stew him in a pot and eat him. If Bilbo wins he gets to leave the cave uneaten. After a few riddles each bilbo realises Gollum is much better than himself, so cheats by asking "what is in my pocket?" When he faails to find the answer bilbo uses the ring to vanish from sight and escape.
Bilbo asks Gollum "What's in my pocket" (the Ring) and Gollum cannot answer.
"Handses!"
Knife
Bilbo was surprised to find that Gandalf was with the River-Folk.
That was the big mistake Bilbo made. There was no one to put him in it and close it up for him.
Trying to pick his pocket. William's purse gave it away by yelling.