Collybia species, possibly C. dryophila in Aurora. Associated with Quercus palustra, a non-native species in my area. Odor is quite pleasant and distinctive: similar to lilacs or other pleasant floral aroma. After many years of finding this and not being able to positively identify it, I thought I'd share. Maybe it is C. dryophila, and I'm just not comfortable with the Collybia genus.