Peas are one of my very favorite cool weather crops. They are easy to grow and they are the most delicious thing.
Spinach is one of the most cold hardy vegetables and can even be overwintered in many locations with good luck.
Radishes are one of the most gratifying vegetables to grow. I mean, seriously, you can have a fresh, homegrown radish from seed in as little as 21 days!
You can start planting out as early as 4 weeks before your last frost date. Cabbages can handle freezing temperatures down to about 20F.