Answer is The speaker is the grass that is determined to grow over the earth.
Explanation:
The last two lines of the poem clearly say
<em>"I am the grass</em>
<em>Let me work".</em>
Here the subject of the sentence represents itself as "the grass" and it emphasises during the poem that it "covers all", which means that its work is to cover the earth.
In this poem, the speaker wants to remind people that even though it covers the battlefields makinf the dead bodies invisible, the memory always sticks with people. Except for making us feel for all the dead bodies and tragedies, this poem reminds us that horrors of war mustn't be forgotten.
