A calico Manx; you can safely assume that is a dumpee. She's either escaped from somewhere/ran away from somewhere, or was thrown out. And with the way she behaves, meowing at you to draw your attention, but then hissing as you look at her/approach her, that makes me suspect she was thrown out. She quite likely has trouble fending for herself, which is why she meows at you to draw your attention and get some food off you, but her trust in people has gotten a severe dent I'm wagering, if she was indeed thrown out, which is why she won't let you approach her and hisses at you.

The best you could do is just to leave food out for her whenever you have any, perhaps make sure she'd have a dry spot to shelter (a loose board to allow her to get under the porch would already do), and talk to her in a calm and friendly voice whenever she is there meowing at you. I'm not saying you'll be able to win over her trust, but you can definitely give it a shot and show her not all people are against her or out to hurt her >^_^<

I've been trying to see if I can get closer to her. She has a warm spot under the house. (Some animal dug under it a long time ago, and I never filled it in.) But when I approach she runs under there which I'm happy about because I have seen a complete lack of mice this winter because of it.

I will probably buy a small bag of cat food to leave out for her. (It can't be healthy eating all those table scraps.) I suspect she probably did get dumped off, because when I first seen her (about 6 months ago) she looked entirely too clean to be a feral. Most of them have a look about them and seem to get thicker fur. (I'd love to pet one, but they are way too wary of me and even if they eat the food I leave out they run if I even peek out at them.) I'm assuming she's a female. (Female and male cats have different looks that only people who adore cats can tell. XD )

Ah, it's good to know she has a warm, sheltered spot; that will be very helpful for her with the winter coming in. And it sounds like she is keeping the mice away as well, which is an added bonus!

Yes, it sounds like a good idea to get some catfood. I did the same for the strays hanging around the tennis park where I worked as a groundskeeper; I got the cheapest brand-less catfood I could get in bulk, dryfood, not canned stuff, and some old ceramic food dishes, those thick sturdy ones, so I could put out food for them. That's probably the best way to go at it for you as well (especially on the cheap brand-less dry catfood part), and perhaps leave a dish of water as well.

And yes, for one, calico is sex-specific. Male calicoes hardly exist, and the very few ones that do are infertile. So she is most likely a female. Especially if she has that somewhat sleeker build and more elegant head rather than the full, round head and square face tomcats usually have >~_^< I also strongly believe you are right, my first thought also was that she was thrown out from somewhere. Calico Manxes don't just appear in the wild outdoors as a feral. And even ones that escaped from somewhere or were thrown out from somewhere tend to have somewhat messed-up, mussy and grimy fur after a long enough time of being out in the open, so with her being that clean when you first saw her, she is most likely a dumpee, alright. Such a shame, really... poor girl.

I have a stray cat like that, but he was able to warm up to me really quickly. When I came up to him while he was walking towards my backyard he hissed at me so I stopped and kneeled down while reaching my hand out, and a moment later he came closer to me and started rubbing against me. Mine meows because he wants to play or whatever, there are many reasons why yours is meowing. Try doing different things and watch how your cat reacts.

It's coming closer and closer everyday. It's not as quick to run. I am suspecting someone might have kicked it or something because it only hisses when I walk. It's curious of me, but I'm a little afraid of getting it to the point where I can pet it, because I don't want her to approach someone that might harm her. She's such a cutie I'll have to snap a picture of her sometime.