We keep onions out year round. About 3 weeks ago in mid Feb I put out swiss chard, arugula, and some free lettuce seeds I got. Those are all up and doing well, though a lite dusting of snow last night was a little scary. Ground was warm enough to keep the little guys from getting bit. Last Saturday, 3/1 I put out german giant radishes, danvers carrot, & frizee endive. Over the next 6 weeks or so I'll be adding mesclun, slobolt lettuce, zucchini, edamame soybeans, dragon's tongue bush beans, various heirloom tomatoes, jalapenos, sweet peppers, something called red malabar spinach (which I'm told is not really spinach), and moon & stars watermelon.
Our asparagus got going early. We have had 2 meals with them on the side, plus plenty cut up and added to salads. It is their 4th year, so it should be really good into the end of May at least.
Starting as early as I did this year was a gamble. I've waited until mid March to start before and still lost plants. We've had a mild winter here in North Texas, so I felt pretty confident. So far so good!