Galls caused by tiny flies (Gall Midges). Unruptured galls are brown with a "crusty baked bread" appearance (to me anyway). One unruptured gall seen in photo #2 but it appears dead as it is black. Ruptured galls appear as above.
Bayard Cutting Arboretum. Forest floor. Oak leaves.
Lat: 40.73, Long: -73.21
Spotted on Sep 7, 2013
Submitted on Mar 5, 2014