Godenrod elliptical gall - Gnorimoschema gallaesolidaginis
Toronto, Tommy Thompson Park, Ontario, Canada October 3, 2009 Size: ~ 4 cm
This is field photo, later on I collected some galls from identical goldenrod plants which were rather common in the area.
Is it Canada Goldenrod (Solidago canadensis)? It does have leaves with untoothed egdes, see photos here.