This article explores how the notion of a serendipitous curriculum relates to young children's artmaking events in an early childhood center in the Midwest. A new materialist theoretical lens is used that not only considers the agency and action of children, but also enables ALL matter within a relation to act. In doing so, it offers a way to reconceptualize curricular uncertainty through new materialism and serendipity as a space for unfolding knowledge production. Serendipity not only refers to an openness and disposition of finding agreeable that which was not directly sought, but also to a phenomenon in which knowledge is constructed, or comes to be, at the same time as something else comes to be. This article argues for an opening up of traditional preK-12 notions of a planned, outcome-based, and objective-driven art curriculum in favor of the yet-to-be-known and serendipitous. It describes one event within a series of weekly artmaking events in which Heather Kaplan was both the arts facilitator and a researcher working with teachers and young children in a Reggio-inspired preschool. The event is a snapshot within a series of weekly artmaking explorations that involved repeated and cumulative encounters between a thin piece of plywood cut into two equal 4-foot sections, various art and everyday materials, and preschool-aged children. This event is relayed to consider the possibilities for new, unknown knowledge created through serendipitous, open-ended curricular practices, and children's eventful entanglement with materials, objects, and artmaking.