I have about 12-14 healthy tomato plants that I have uprooted and chopped up to till back in for their nutrients, but I'm wondering if I can do anything with the 20+ green (unripe) tomatoes that happen to fall off as the cages were removed.
If the tomatoes have any red on them, you can set them out on the counter or a windowsill and they may still ripen. If they are all green, your best bet is to use them for fried green tomatoes or green tomato relish.
Since you've already tilled the tomato plants in to your garden, you could also compost them if you aren't interested in eating them. Some people choose not to compost tomatoes or tomato plants because there are several pathogens that affect the plants which can live for years in the soil. Since you've already composted the plants, it wouldn't hurt to add the fruit.
Food, Not Waste
That's food you've got, not waste. Eat them before they get frostbite.
Green Tomato Pie
Surprisingly, when cooked as a pie they do not go mushy and cook down like tomato sauce. Instead, they cook like apples, softened but retain their shape. Indeed, the recipes are basically the same as Apple Pie. Tip: Add some sliced apple along with the tomato in your pie, perhaps 50/50.
Fried Green Tomato
I usually bring green / yellow tomatoes indoors, and store them at room temperature, or even better a little below room temperature. They will normally turn into good red tomatoes after a few weeks. If the tomatoes are a little yellow, this should work. If they are very green, they may not turn red.
Green tomatoes will generally (not always) ripen after you pick them, if you wait (whether or not there is any red on them). Sometimes it'll take a day. Sometimes it'll take much longer. Immature tomatoes may just dry or shrivel up, however. Whatever the case, I would recommend taking all of those tomatoes and putting them in storage (not in the refrigerator) until they turn red. Room temperature is fine (I think it'll ripen faster at room temperature than in a cool storage room, although I could be wrong).
This works well with my early girl and lemon boy tomatoes, as well as whatever else we have.
In fact, I hear most store-bought tomatoes were picked green (so as to extend their shelf life or something) and allowed to ripen off the vine.
You may have heard the term, 'vine-ripened tomatoes'. There are also tomatoes that were not ripened on the vine (picked green).