Hi there.
We too are very new to this but we have found our first four caches. These all seem to fit the micro or small size. The first was a tiny magnetic barrell from a pet collar, the type you put your name and address inside. This just contained a log. Our second container was a Saxa salt container that had been spray painted and contained a log and swap items. The third was even tinier than the first, about the size of a small button. This was a magnetic cache and again contained a log. Our latest one was a 35mm film container, again just a log. We've yet to find anything bigger but really look forward to it.
Hope that helps.
Tina