Ranunculaceae, the Buttercup Family, is treated by Rhoads and Block (The Plants of Pennsylvania) first by flower symmetry - bilaterally symmetric or radially symmetrical. If radially, then based on leaf arrangement. Opposite leaves are of Clematis (Virgin's Bower); otherwise they turn to fruits and then flower colors (which is reverse of growth order and a little impractical for a key being used in the field). Anyway, Ranunculus is known by the shiny yellow flowers, such as those held up to chins to determine if one likes butter. Though a strange practice, I have found it to be true. As I child I enjoyed butter and my chin reflected the yellow of the flower petals. Now that I have lost my taste for butter and grown a beard you can no longer make out a reflection from the flower. There are several kinds of Buttercups, and the family contains several other very important genera such as Aconitum, Anemone, Thalictrum, Hydrastis, Coptis, and Actaea.
In case some of the above does not make sense, I will be exploring the details later. These pictures are from yesterday a Buttercup by the river and below an image of Marsh Marigold is included.
Nathaniel Whitmore, herbalist