I liked the repetion of the phrase "six feet above you I lay" and how you used a slight variation on that phrase to also bring the poem to a close. I think by simply changing a few words you achieved a great finality to the last line. I liked the imagery in the poem, I thought it was very descriptive and painted the scene very well, but I also felt that there could have been more creative or precise words to express the same things. Such as instead of "I listen to the cars go by on the road" the word go could be changed to drive or pass, even speed by. It adds a little more detail and action to the description. I thought in the first stanza the break between the third and fourth line was a little choppy. Perhaps you could move the word "was" down to the fourth line. I feel it would flow better, but it is all up to preference. In the third stanza I thought it could be better phrased if it was something more like:

"Six feet above you I lay
While the frost begins to form on my face
My tears watering the dead grass
As my lips speak your name"

I felt that you were already using repetion with the first line of every stanza being the same it wasn't necessary for the repetion with the word as. In the last line of the fourth stanza, I wasn't sure if you intended to put "you're here" or "you here" as it stands it doesn't quite make sense since "your" is possessive. Other than that I don't have any other critiques, just things I liked. Mostly it was the second lines of both the first and second stanzas. Those two were very striking in how they showed the person was dead and how you couldn't get close to them again. Very sad. I thought overall the poem was a good write.