You could do a pop-up nature scavenger hunt as we often do and did yesterday. It's more of a finding quest as we look about the park for interesting items without consulting a list. Today we found an elm samara, a catalpa pod, a white oak leaf, and a Y-shaped stick.
|Image: Scavenger Hunt - Washington Square Park by Carina Zimmerman courtesy of Carina Zimmerman|
If you prefer a formal guide, and want to scavenger hunt in Washington Square Park, check out Carina Zimmerman's Scavenger Hunt in Washington Square Park. The park is Carina's favorite in NYC. If you don't live near Washington Square Park, check out Carina's other scavenger hunt; it's a nature hunt for 20 items you could find in most park settings.
P.S. I discovered Carina's blog via Washington Square Park Blog.