National Zoo
http://nationalzoo.si.edu/Animals/BackyardBiology/UrbanNatureWatch/default.cfm National Zoo site provides information on poison ivy (including a link to photos of poison ivy), seed dispersal, groundhogs, earthworms, migratory birds, and why leaves change colors.

Guided Science Walk Through the Woods
http://www.urbanext.uiuc.edu/woods/
University of Illinois narrated slideshow guides the viewer on a walk through the woods, includes photos of fungi, rot, decomposition, insects, poison ivy, seasonal changes, dormancy, and nature center safety tips.