Answer:
The alliterative phrase from the poem that creates a grateful mood is “Golden in the mercy of his means,”
Step-by-step explanation:
These lines are from the poem "Fern Hill" by Dylan Thomas, the theme of this poem is the narrative of the happy childhood of a boy and how much he enjoys the simple things of life before adulthood comes, this line in specific is talking about those beautiful days and how this time was blessed with the mercy of innocence.