I'm not sure of your zone. I'm in zone 7 in Maryland. Here are some that we see during that time frame. By the way, you say plants and flowers. Do you want shrubs too?

aster - 'New England', 'New York', 'Alma Potsche', white wood aster, and the list goes on.
physostegia virginiana - Obedient plant
plumbago
heliopsis
boltonia
agastache
hardy begonia
chrysanthemums
pansies
sedum - 'autumn joy', 'matrona', 'brilliant', 'neon' and many more
helianthus
lobelia cardinalis
some salvias
Perovskia atriplicifolia - Russian sage
Rudbeckia hirta - black eyed Susan
many types of roses

Sub Shrubs (these get cut back in late winter/early spring)
caryopteris
buddleia

Shrubs that come to mind
hydrangea
camellia japonica

Vines
several vines like some clematis, aster carolinianis, honeysuckle - 'gold flame' and others

most ornamental grasses

That's all that comes to mind at the moment. I guess you know how to search these out. If not, let me know and I'll send you to some sites.

Newt

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When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.