Q:

How many pieces of paper are there?

I read the following article about the fullness of emptiness and this statement stuck out to me:

...when we look at a sheet of paper, the sheet of paper is part of our
  perception. Your mind is in here and mine is also, so we can say that
  everything is in here in this sheet of paper.

Now, the question is: prior to my perception of the paper, was it the same sheet of paper?
Based on the article, my answer would be no. I would expound on that with the following thoughts:

prior to my perception of it, a paper exists that does not have my
perception of it as an aggregate, paper #1
after my perception of the paper, a new paper came to exist consisting of all of the aggregates of paper #1 plus my own perception, resulting in paper #2

Conclusion: there are two distinct, co-existing pieces of paper. Thoughts? 

A:

There is no paper ;)
Through knowledge we can see the rain, air, forest, lumberjack, the paper mill and its employees in paper. Through wisdom we can see ourselves in paper, because it is only through the lens of our minds that "paper" can be seen at all. Although it is the case that "paper" does not exist separately from our minds, this does not mean that our minds produce "paper". For paper is emptiness, and emptiness is paper. Paper is none other than emptiness, and emptiness is none other than paper.
The paper that exists in your mind is not the paper that exists on your desk. Just like the nose that exists on your face is not the nose that exists in your mind. These concepts that exist in your mind are loosely linked to objects that exist in the material world, but these concepts and their associations are nothing but emptiness. 
Due to causes and conditions "paper" has manifested on your desk. Through those  conditions and others, the awareness of paper has arisen in your mind, and from this the discernment "there is paper" arises. But these dharmas are emptiness just as the causes and conditions from which they arose are emptiness. "Arising" is emptiness, and "emptiness" is also empty. None of these things are paper nor any other independent substance.
FYI that article is an excerpt from Thich Nhat Hahn's translation/commentary on the Heart Sutra titled "The Other Shore". Master Hahn's teachings seem to be targeted at a generally materialistic western audience. I still believe that they are excellent and beneficial, but I think that it is also important to be aware that he will blur the lines between the material and immaterial to make it easier for this audience to grasp.
Take care,
Nolan

Could we not also see through knowledge that there is no rain, air, forest, lumberjack, or paper mill and that it is only through the lens of our minds that any of these can be seen? If this is the case, then could we also make the argument that the material world itself is the result of our mind? This changes the whole idea of emptiness for me. I would say, all things are empty without a mind to "make a objects" out of all of the "non-object elements". 

In my understanding, when phrased this way, this is a half-truth. It is extremely likely that the material world does exist, and it is the simplest explanation for all of the things that our minds come into contact with over the course of our lives. However, we as human beings are prone to recklessly-and worse, implicitly-assigning meaning to the material world that it does not inherently possess. 
We assume permanence where there is impermanence. We assume happiness where there is suffering. We assume a self where there is no self. We assume that there are things that are mine and things that are yours, where there is only matter.
I wouldn't say that our minds produce the material world, but that our minds produce an immaterial world (full of those erroneous views) that we often implicitly assume is equivalent to the material world. It is this immaterial world that, in my understanding, is empty.
When you realize this emptiness, then you realize that these empty dharmas have no weight. When you recognize their lightness, then you realize that you can brush them round as easily as dust on a table. You can pile up the dharmas that bring joy, and brush away the dharmas that bring suffering.

