Rock:
My father, twenty-five, in the same suit
Of Genuine Irish Tweed, his terrier Jack
Still two years old and trembling at his feet
My mother, twenty-three, in a sprigged dress
Drawn at the waist, ribbon in her straw hat,
Has spread the stiff white cloth over the grass.
Her hair, the colour of wheat, takes on the light.
She pours tea from a Thermos, the milk straight
From an old H.P. sauce-bottle, a screw
Of paper for a cork; slowly sets out
The same three plates, the tin cups painted blue.
The sky whitens as if lit by three suns
My mother shades her eyes and looks my way
Over the drifted stream. My father spins
A stone along the water. Leisurely
And we are definitely in the spiritual world. The ‘three suns’ may symbolically represent the three members of the family; the world is brighter when they are together. 
 It may also suggest that the speaker is talking about the Holy Trinity, as we know in the first line he states that he believes that his parents are somewhere beyond ‘Eden Rock’. 
 And yet this is ambiguous as there is another explanation. A  parhelion  is a meteorological phenomenon,  caused by ice crystals in the air, where an illusion of three suns appears in the sky. The poet seems to be teasing the reader with uncertainty. 

Eden Rock