The Color of the Grave is Green — Grave Digger

Grave appears three times here each with a different meaning, burying beetle, badger, and epitaph. The first two seek and consume carcasses, but they cannot find carcass-like people covered by bonnets. Structure of this riddle is similar to the "Brain is wider than the Sky."

The Color of the Grave is Green-
The Outer Grave-I mean-
You would not know it from the Field-
Except it own a Stone-

To help the fond-to find it-[5]
Too infinite asleep
To stop and tell them where it is-
But just a Daisy-deep-

The Color of the Grave is white-[9]
The outer Grave-I mean-
You would not know it from the Drifts-
In Winter-till the Sun-

Has furrowed out the Aisles-[13]
Then-higher than the Land
The little Dwelling Houses rise
Where each-has left a friend-

The Color of the Grave within-[17]
The Duplicate-I mean-
Not all the Snows could make it white-
Not all the Summers-Green-

You've seen the Color-maybe-[21]
Upon a Bonnet bound-
When that you met it with before-
The Ferret-cannot find-
(F.424/J.411)
[1] Grave:: grave digger, also called burying beetle or sexton beetle.
[2] Outer Grave:: outlook of the grave beetle.
[4] Stone:: they will shape the carcass to a ball and cover that with secretions which looked like a stone.
[5] the fond:: those who like beetles.
[6, 7] Too, to, tell:: hard to find these beetles when they are not working.
[8] just, deep:: they bury the carcass ball not very deep.
[9] Grave:: grave digger, nickname of some badgers that burrow for carcasses, hinted by ferret in line 24. Ferret and badger both belong to the weasel family.
[9, 10] white, outer:: color of its fur.
[13, 15] furrowed, Houses:: badgers live in burrows.
[16] friend:: an animal friendly to the environment by cleaning the carcass.
[17] Grave:: the nature of engravings on tomb. Color:: the act, wording to conceal the truth.
[18] Duplicate:: epitaph on paper, not on the tombstone.
[19] Snows, white:: covering words to make the dead innocent.
[20] Summers:: praises of one's best days. Green:: fresh and vigorous.
[21] Color:: general complexion or tone; character, kind (OED 16a).
[22] Bonnet:: a cap to cover one's true self.
[24] Ferret cannot find:: the digger cannot find living carcasses covered by bonnets.

An animal of the badger tribe was brought for our inspection. It is a native of the lower range of hills; and is called by our people the grave-digger, from its habit of burrowing into places where corpses are interred, in order to feed on them. ─ The Private Journal of the Marquess of Hastings (1858)

The Indian badger is found throughout the whole of India, . . . it is accused of digging out dead bodies, and is popularly known as the grave-digger. ─ The Mammals of India (1867)