As Jill suggested, definitely pansies and lettuce now, they are cool-weather crops! To hurry things along, you can probably buy starter plants of both at a nursery.
Here's something to consider about radishes vs, say, lettuce: a single radish seed gives you a single radish. One bite and that's it. To make your radish crop worthwhile, you need many plants sown in succession, otherwise they all mature at roughly the same time.
A single seed of leaf lettuce (like Romaine) yields a plant that you can continuously harvest over several weeks by pulling off the outer leaves as they mature. New leaves keep emerging in the middle. If you're only feeding yourself, 6-10 lettuce plants could be plenty! Plus you can pick it daily so it's always fresh with no need to store it in the refrigerator. You can buy mixed greens seeds for variety. Same with basil (in the warm weather) — keep pinching off leaves and more appear.
Just some thoughts to help you decide. Also one question: does your radish bin have drainage holes?
An example of salad greens mixed seeds
