What is the poem with line that says may winds be ever at your back?

The poem you're thinking of is likely "Irish Blessing" which contains the lines:

> May the road rise to meet you,

> May the wind be always at your back,

> May the sun shine warm upon your face,

> The rains fall soft upon your fields

> And until we meet again,

> May God hold you in the palm of His hand.

This poem is a traditional Irish blessing, expressing hopes for good fortune, safe travels, and a life full of happiness.