Broad question . . . are you only interested in veggies, or all food crops or all types of plants? Can you plant anything in the ground or are you restricted to containers by your situation?

You could plant bulbs for next spring, including garlic which will be ready for harvest in July. Just remember that what you plant in a container to overwinter, the plants should be about 2 zones hardier than in-ground crops, so anything hardy to zone 4 should be fine in a container for you unless you can provide some protection like bubble wrap around the container or leaves or mulch heaped around it. Parsley may be OK for this fall, but it would be too late for me to plant much of any veggies since we will get frost in the next couple of weeks and even radishes don't grow that fast. ;>) Since you are a couple of zones warmer, I don't know what may work for you specifically. You can probably plant some perennial crops like rhubarb or blueberries if those are of interest.

You might want to borrow from your library a copy of one of Eliot Coleman's books which are about 4 season growing. He uses unheated tunnels, but his calendar for planting for overwintering crops could probably be adapted to use for late fall harvests, especially if you somehow protect your containers when frost is due. I know he plants many different greens and carrots, but don't remember off the top of my head other crops. He is coastal Maine, but plants most things earlier than this I think.

I'll be planting my spinach in late October - for a spring crop. The seeds overwinter and sprout in spring.

I usually try to plant my Fall crops in mid August - peas and lettuce. But I forgot this year.