Autumn
meeker
Not 'cooler' or 'shorter'—meeker. Dickinson personifies mornings as having humility or gentleness, like they've lost their summer boldness.
out of town
Social language for a flower. The rose hasn't died or wilted—it's gone visiting, like a neighbor who left for the season.
gayer scarf
'Gay' meant bright or showy. The maple's fall colors become fashion—a deliberate accessory, not decay.
old-fashioned
The turn: after watching nature dress up in fall colors, the speaker worries about being outdated if she doesn't accessorize too.