List the elements of nature that are referred to in the poem.

The elements of nature that are referred to in "somewhere i have never travelled, gladly beyond" are flowers, snow, spring, and the rain.
The main image in the poem is how the speaker feels himself "open up" because of the influence of the person that the poem is addressed to. Lines 4–8 state,

your slightest look easily will unclose methough i have closed myself as fingers,you open always petal by petal myself as Spring opens(touching skilfully,mysteriously)her first rose.

In this image, the speaker compares himself to the first rose that opens its petals in the springtime. Just like the flower, the speaker himself begins to open and bloom because of the person he is addressing. This person's influence allows him to show himself, instead of being closed off and protective of himself.
This person can also have the opposite effect on him. In lines 9–12, the speaker says,

or if your wish be to close me,i andmy life will shut very beautifully,suddenly,as when the heart of this flower imaginesthe snow carefully everywhere descending . . .

Just as flowers close up to protect themselves when it snows, the speaker says that this person can also cause him to close up to protect himself against the "snow."
The speaker concludes, in lines 17–20, by saying,

(i do not know what it is about you that closes and opens; only something in me understands the voice of your eyes is deeper than all roses)nobody,not even the rain,has such small hands

The other person has so much influence over the speaker that they can immediately cause him to feel open and vulnerable or can immediately cause him to close up. This person's influence is so profound and so delicate that the speaker says, "not even the rain has such small hands." When we think about water or the rain, we usually think that water can get into the tiniest crack and soak through anything that is not completely sealed. However, the speaker says that this other person's influence is even more subtle than the rain; their influence can get to him when nothing else can.
https://poets.org/poem/somewhere-i-have-never-travelledgladly-beyond