June's "super top secret" mission involves what activity?

The activity that June refers to in her "super top secret" mission is planting black-eyed susan seedlings. This choice highlights June’s intent to engage in gardening, which conveys a sense of nurturing and growth. Planting seedlings connects with themes of care for nature and the excitement of watching something grow over time. It also might suggest an element of mystery or anticipation, as this kind of project can often lead to a delightful reveal when the flowers bloom.

In contrast, building a treehouse would imply a more complex construction project that involves tools and potentially a group of friends. Throwing a surprise party mainly revolves around social interaction and organization skills to bring people together, while writing a book usually requires solitude and creativity focused on storytelling or creativity, making them less aligned with the idea of a "secret mission" that revolves around hands-on activity in a natural environment. Therefore, the emphasis on planting seedlings encapsulates June's secretive and personal endeavor in a meaningful way.