Fluted Bird's Nest
This tiny cup fungi is less than 1cm (~3/8 in.) in diameter and is widely distributed throughout North America.
For an interesting description of Cyathus striatus and how it reproduces, see the Wikipedia entry on this species
Family: Agaricaceae (formerly classed as Nidulariaceae)
For a taxonomic tree and links to other fungi posted on Wild Florida Photo see the Fungi at Wild Florida Photo page.