When it's Iris Time in Tennessee by Willa Waid Newman was adopted as a Tennessee state song in 1935.

FIRST VERSE

Sweetness of Spring memories bring
Of a place I long to be.
Land of Sunshine calls this old heart of mine,
Come back to Tennessee.

SECOND VERSE

Rocks and the rills deep tinted hills,
There’s no spot so dear to me,
Where’er I roam still it’s my Home Sweet Home,
My own, my Tennessee.

CHORUS

When it’s Iris time down in Tennessee,
I’ll be coming back to stay
Where the mockingbird sings at the break of day
A lilting love song gay.
Where the Iris grows,
Where the Harpeth flows,
That is where I long to be.
There’s a picture there that lives in memory
When it’s Iris time in Tennessee

Source:

Tennessee Symbols: Tennessee Blue Book (PDF)

Links:

List of all Tennessee state songs
List of state songs - 50 states