Here's why:
* Curiosity: They are undeniably curious about the mysterious source of the pennies. They find the knothole and the hidden treasure intriguing and want to know more.
* Ambivalence: While curious, they also feel a sense of guilt and wrongness about taking the pennies. They know it's wrong to take things that don't belong to them, but the allure of the treasure tempts them. They grapple with their desire to understand the mystery and their sense of right and wrong.
Their ambivalent actions show the complexity of childhood development, where curiosity and the desire for exploration often clash with moral understanding and social norms.