1) broccoli (flowers), kale (leaves), cabbage (headed-leaves), kohlrabi (engorged stem/hypocotyl), cauliflower (flowers) are all the same species, different subspecies. you can eat the stem, leaves, and flowers either as different subspecies, or all-together in one subspecies -- kale stems, broccoli leaves (the amish sell them, for example). kohlrabi leaves are generally super healthy if not as tasty as some kale leaves.
2) there are a lot of bad tasting kale varieties out there, but a few good ones. i can't say any taste great -- compared to vanilla frosting, say -- but there are some which taste positively bad, and others which taste relatively good. what you're getting in the store is unlikely to taste great. even small farmers go for production and what a catalog says about taste, as few run true variety trials for all facets -- including fresh and cooked flavor -- of a variety.
3) walking around the farmers market i sometimes glance at where the farmer cut their garlic stalks after they had dried. as one of the most pricey $/lb items they sell, that wee bit of dried stalk actually adds up for (us) poor farmers, and one -might- be temped to cut it higher rather than lower. i cut it at the perfect height for slamming the neck -- hard-neck garlic, in this instance -- on a table for popping the cloves apart, either for eating or re-planting.