What are limits of the types of material Conjuration can make? Could I make any material I could conceivably think of, or would I have to find a way for my character to know about that material? And, for that matter, what kinds of things can I assume my character knows?
The main limit to Conjuration is that it's basically worthless without supporting schools to draw from. You could summon adamantite or nitroglycerin or dragon blood in theory, but you'd need not just a way to know about it, but a way to understand it well enough to actually conjure it.
Plus, of course, the Conjuration skill to pull off such a potentially advanced material.
In terms of what your character knows... wizards who can and do pierce the veil of reality to gaze upon, travel to, or bring forth things from other dimensions aren't exactly
common, but they're common enough that if some sort of caged abomination were to suddenly appear in the middle of the street, pretty much everyone would think "Oh, a wizard's doing things they shouldn't. Again." Similar tendencies apply to most other fields.
So put simply, there's a lot of weird stuff you
probably shouldn't know about that you conceivably could because wizards. If you have more specific questions about how much you probably know about wine or cloth or construction without wizard interference, feel free to ask, but I got the impression this was more of a "can I invent gunpowder" sort of question.
Speaking of which, bear in mind that knowing
of something is different than knowing how it works. Just because some crazy wizard gave you a dreamwalking potion that let you see explosive black powder being used on a different plane doesn't mean you're likely to understand how to make (or conjure) it.