Can't think of any seeds to plant now in your zone unless you want to try lettuce. May or not have time for it in the ground depending on how the fall progresses. Might get away with radish as well.

Most perennials need to be planted in the Fall so that the freeze will break the hard coating to allow them to germinate. Since I have planted columbines, indian paintbrush, and two varieties of chives this past year, I know that their labels said to plant in the Fall. I can't think of any fruit trees indigenous to northern zones whose seeds wouldn't do better to winter in the ground to break the seeds open.

The two problems I have with planting in the fall are: birds eat most of the small seeds, and when I clean out a bed in the Spring, I tend to disturb or ruin things already bedded but not visible. In order to save seeds and get better germination, I start seeds inside during late winter and transplant outside as soon as possible.

Annuals are another matter, and although some can be planted in the fall, I like to start slow-growing ones inside and transplant them outside.

If this is not enough information for you, perhaps you should look up each kind of seed since each must be treated according to its kind.

Some of the poppy varieties prefer fall planting -- there are other seeds which *require* stratification before they sprout, but you really should look up each of the kinds of seed you have, to be sure which require what. You may find interesting info on the winter sowing forum... that's not planting in the flower bed, but still good to know. Keep an eye on each poster's zone, a zone 4 winter is way different from a zone 7 winter :)

Check this database out. You can search by the botanical name for many perennials.

If the instruction recommend a cold treatment, you could sow the seeds now.

Also, in the winter sowing FAQ pages I believe there is a list of plants that do well with fall sowing- they would be good candidates for winter sowing.

Here is a link that might be useful: Seed germination Database

I'd definitely recommend that you check out the 'Winter Sowing' forum.