Why did Tom and Huck steal stuff from Aunt Sally? And what do they steal?

They steal a variety of items including: a sheet, a shirt, six candles, a spoon and a brass candlestick. The reason is so that they can play-act Jim's escape. He's locked in the little shack out back and they want to dig him out through an elaborate game/story Tom invents. These are all props in the game.