Lettuces and other greens, particularly arugula. Radishes. Turnips. Other cole crops -- kale, collards, etc. I never have much luck with fall planted peas, but all of the other cool/short season stuff does fine.

Pansys and mums will start appearing in garden centers soon along with ornamental kale and cabbages. A few other cooler-season annuals like snap dragons and alyssum can be found. Directly sowed now, fast blooming annuals like cosmos and zinnias and marigolds will put on a great show until frost.

The autumn blooming (or otherwise attractive) perennials and shrubs are really too numerous to mention and probably not what you're looking for at this point anyway.

My favorites include carrots, parsnips, kale, spinach, mache, leaf lettuce, and of course garlic.