One principle value that grass seems to have in this poem is that it is democratic and not prejudiced since it grows everywhere between all peoples. It is also found on graves - indicating it does not matter who the dead were, the grass will grow there. Below is a short analysis of some of the things grass is suggested to be in Section Six of the poem "Leaves of Grass"
One suggestion is that it is, "...the handkerchief of the Lord" meaning that every time you see and ponder grass, it leads you to the question of whose it is? If you compare finding a dropped handkerchief to grass to the Lord putting grass on the ground you can understand this line.
Another definition of grass which Whitman gives is to compare it to a child - in that grass is the fruit (or child) of vegetation.
He also calls grass a “uniform hieroglyphic” which can be found everywhere in every area of the earth. In the same stanza he indicates that grass is democratic and not prejudiced as it grows everywhere among all peoples.
He calls grass "the uncut hair of graves" seemingly indicating that grass grows over everyone's grave and the fact that it is uncut might be referring to the fact that grass will grow over anyone - even those for whose family does not care and groom the grave.
When it says "or i guess it is the handkerchief of the Lord" it also reminds me of the dew in the mornings that settles on the grass. Then it goes on to say "a scented gift and remembrancer dropped" as if he placed it there as a reminder that he is the Creator.
Also when it says "..the grass itself a child...the produced babe of vegetation." it reminds me of how we rely and depend on our children, the next generation, just as we rely on the grass at the bottom of the food chain.