how do you know that material things dont matter to huck?

Huck never shows interest in them. He doesn't care for fine clothes, in fact he feels stifled by his Sunday and school clothes. Huck likes the idea of winning the money more than the money itself. He gives it to the judge, partly because his Pap wants it but mostly because he really doesn't know what to do with it. Huck prefers an organic adventure which has nothing to do with money. Huck also detests the King and Duke's greed. He trials to foil their plans to swindle the Wilks out of their inheritance. Huck could also have sold Jim out for money but the money part didn't even enter his mind.