OK, for immediate gratification, try onion and scallion bottoms saved from cooking. I always have success with organic ones. Less success getting onion roots to grow with not organic. Just save generous pyramidal/tetrahedral portion of the onions and at least 1/2 inch of scallions that have root scab (some scallions are sold with roots, but some have completely trimmed off base and those have no root-growing cells). If in doubt, unused onions with intact base, saved in the fridge in a ziplock for a couple of weeks will start to grow (roots and green shoot) and they can be planted at that time after trimming off the usable parts.
These will be floppy and weak, but they will be tender and provide garnish and little touch of green in soups and omelettes, stir fries. Just keep trimming them as they grow. It doesn’t matter if the light is low because they will just grow longer (and floppier).
If you start seeds in the house, mustard family kale and Asian greens — seeds that look like little round bb shots — will sprout within 3-5 days (if you try to start them in low temperatures they may take as much as 3 weeks to sprout). You can start them in community pots (yogurt cups even). Once they have true leaves, plant them out in your container.
I would choose greens with sturdier leaves because they will grow wimpy and weak in less light = tender. Aim for cut and come again micro- and baby- greens rather than full heads of beautiful greens. Aromatic greens like arugula and garden cress, cilantro might work, too.... but if light is too low, they might be difficult to handle.
Learning never ends because we can share what we've learned. And in sharing our collective experiences, we gain deeper understanding of what we learned.