Good call, Susan! It is Fragile Fern, a plant whose taxonomic status is not treated consistently by our many authors. Closely related and/or synonymous species and varieties include Cystopteris protrusa, C. tenuis, C. fragilis, C. fragilis var. mackayi, and C. fragilis var. protrusa, among others.
This fern emerges earlier than most. When spring ephemerals are in their prime it's unfurling among them, especially in rich woods. Eventually it gets much taller than the ones in the photos below.