Spinach, parsnips and carrots too. Fun thing with carrots is they can be left in the ground for storage, and pulled as needed all winter long. Garlic is planted in the fall and harvested early summer. I grow a scottish leek that I just sowed last week and will over winter. Rutabaga are a good fall crop as well are beets. Fava beans too can be sown in the fall for a bountiful late spring/early summer harvest.
"Study books and observe nature; if they do not agree, throw away the books." ~ William A. Albrecht
I'm not sure what zone I'm in. According to the maps it's either 3b or 4a. The average first frost date here is Sept. 26. Last year I planted on the 8th of August.
What I tried:
French Breakfast radishes, 28 days
Giant Winter spinach, slow to start but eventually gave lots of leaves
Arugula, Mizuna and Tatsoi, all very prolific
I had two different kales last year that were planted in the spring. Red Russian would probably be the best to plant in the fall as Dwarf Blue Curled Scotch takes a long time to grow.
Baby Scotch Blue has cute leaves, baby Red Russian has hairy stems and doesn't look as appetizing. Both taste sweet when the frost comes.
Rouge d'Hiver (a red romaine) failed last fall but worked very well this spring. It might be an option.
Mâche only gave me 2" rosettes.
I got lots of Pak choy this spring, I'm sure it would work well in a fall garden. It might even do better because I got lots of flea beetles this summer and they cribbled the leaves with holes.
I also tried Mibuna but don't like it that much. It grows fast and would do well.
A green patch in a sea of dead brown leaves is a critter magnet, it's impossible to grow without protection. I used floating row covers directly on the plants. It worked until it got really cold and the covers started to freeze on the leaves.