If it is indeed a Marble orb-weaver, you are lucky to have her. They can be frightening to see the first time. The females, usually the only members you see, grow to be conspicuous, beautiful spiders with impressive strength and insect-catching ability.
Marble or "marbled" orb weaver spiders rarely bite any humans, largely because they have nothing to do with human beings other than taking advantage of the easy living that gardens, field edges and landscaped yards with varieties of flora have provided their web-weaving. The spaces in between shrubs, houses, small trees and where yards meet forest are perfect for orb webs to hang for catching insects. If not disturbed, the spiders will thrive there and provide you with free addtional defense against insects.
If you manage to get a marble or other common orb-weaving species caught between you and your clothes, for example, they may bite from fear of being held or crushed (obviously), and the bite may be painful as it happens (their fangs are not relatively small) and the venom can cause some local swelling, pain, and discoloration, but that s about it. Think of it as a slow acting bee sting. This doesn t mean ignore the bite, however.
Because you may have a more severe reaction to the bite than most people, and even more common... you may have misidentified or not even seen what actually bit you, and it could be from something more troubling than a marbled orb-weaver, such as a trapped bee or wasp in your shirt, or (very unlikely) a brown recluse spider or black widow spider. Though it s rare to see them oustide their range, never believe you CAN T see a brown recluse just because you re so far north. You can have serious damage from their bite, and an allergy to bee or wasp stings can kill you.
Always get something you think may be a venemous bite checked by a doctor as soon as you can. It s much tougher to recover than it is to stay ahead of the problem. And if it was just a marbled orb-weaver, as impressive as they may look, don t worry.... at least you were ready in case it wasn t, and you can be happy the spider is trying to live where millions of mosquitoes, flies, beetles, etc.. and other pests are after you and your family, livestock, or produce. Spiders are the good guys/gals.