Sunshine in the Shadows is the song "Heavenly Sunshine" by Lucy Eddie Campbell from Duck Hill Mississippi, who taught at Booker T. Washington High School in Memphis.

http://www.memphishistory.org/TheChurch/TheBaptistChurch/LucieCampbell/tabid/151/Default.aspx

It was first recorded by Laura Henton I presume in the 1920s. The Carters probably got this African-American gospel song from Leslie Riddle or Pauline Gray.

SUNSHINE IN THE SHADOWS
Carter family- Original

When our hearts are bowed in sorrow
And it seems all help is gone
Jesus whispers do not falter
I will leave you not alone
Then somehow amidst my trials
How it is I cannot see
Then I hear a voice from heaven
Gently saying follow me

    There is sunshine in the shadows
    There is sunshine in the rain
    There is sunshine in our sorrows
    Though our hearts are filled with pain
    There is sunshine when we're burdened
    There is sunshine when we pray
    There is sunshine, heavenly sunshine
    Blessed sunshine all the way

Sometimes my friends forsake me
And I'm tempted to despair
Then I think of my dear savior
Who lay his head, his head nowhere
Oh, it pays to follow Jesus
Just to learn of him each day
And I'll guarantee you, my brother
You'll have sunshine all the way

    There is sunshine in the shadows
    There is sunshine in the rain
    There is sunshine in our sorrows
    Though our hearts are filled with pain
    There is sunshine when we're burdened
    There is sunshine when we pray
    There is sunshine, heavenly sunshine
    Blessed sunshine all the way