For individualism and conformity, I would start with Emerson’s essay “Self-Reliance” and Thoreau’s “Civil Disobedience.” You can find elements of individualism, nature and conformity in their other writings, but these two directly address individualism and conformity. In “Civil Disobedience,” Thoreau wrote a response about why he went to jail. He refused to pay a tax as a protest against slavery. In other words, he would not support a government that endorsed slavery. He expresses his anti-conformity and individualism in pursuit of a political and ethical cause in spite of public/majority opinion.
In “Self-reliance,” Emerson argues that the individual should trust himself, even if it goes against public opinion. Being self-reliant, you are responsible for questioning society and the world around you. Emerson believed that each individual had something to offer and at the very least, the ability to think for one’s self.
If you want to discuss nature, start with Emerson’s essay “Nature” and Walden by Thoreau. Emerson was essentially Thoreau’s mentor. Emerson writes that an acute awareness of the natural world establishes a balance between the internal and external life. And he begins this essay by noting that the experience with nature is most effective in solitude. This is where nature, individualism and anti-conformity link up.
Likewise, Thoreau lives alone for two years in Walden in order to achieve this balance. This balance is a transcendental unity where human, nature and spirit are unified.