Huck is speaking here to Joe on the island, while Tom listens. These "things" are the treasures or small toys and items that Tom has left to Huck and Joe if he doesn't return. Huck is saying that the two of them can take possession of the treasures because Tom is still gone. However, as Joe states:

“Pretty near [the treasures are almost theirs], but not yet, Huck. The writing says they are if he ain’t back here to breakfast.”

“Which he is!” exclaimed Tom, with fine dramatic effect, stepping grandly into camp.

This scene represents more of Tom's seemingly ceaseless efforts to try to turn real life into an adventure story like those he reads about in his books or conjures in his imagination. He likes the drama of faking his own death and leaving his belongings to his friends, as if he were a hero in a storybook. Huck very much feels affection for and admires Tom in a number of ways, but if he is dead, he is glad to take possession of his treasures.

Huck is speaking, and he and Joe are discussing presents that Tom left behind when he snuck back into town to see how people were coping with their deaths.

Before Tom heads into town, he leaves notes and gifts for his friends Joe and Huck.

And he also put into the hat certain schoolboy treasures of almost inestimable value—among them a lump of chalk, an India-rubber ball, three fishhooks, and one of that kind of marbles known as a “sure 'nough crystal.” (Chapter 14, enotes etext p. 69-70)

At this point in the story, Tom has faked his own death.  Aunt Polly thinks he is dead, and he has just gotten back from watching them mourn him.  Joe and Huck are discussing whether or not he will return to the camp and if they can take his things or not.

Notice that Joe is convinced that Tom is coming back, but Huck thinks he won’t and wants to take his things.  This is typical of Huck’s independent, suspicious nature.  Huck also has almost nothing, and the “treasures” are of value to him.