Much of the following is repetitive, but I went to the trouble of typing it out, so I'll post it!

From O'Sullivan, "Songs of the Irish":

DEIRÍN DÉ

Deirín dé, deirín dé,
Tá'n gabhairín oíche amuigh san bhfraoch,
Deirín dé, deirín dé,
Tá'n bunán donn a' labhairt san bhféith.

Deirín dé, deirín dé,
Geóidh ba siar le héirí an lae,
Deirín dé, deirín dé,
Is raghaidh mo leanbh 'á bhfeighilt ar féar.

Deirín dé, deirín dé,
Eireóidh gealach is raghaidh grian fé,
Deirín dé, deirín dé,
Tiocfaidh ba aniar le deireadh an lae.

Deirín dé, deirín dé,
Leogfad mo leanbh a' pioca sméar,
Deirín dé, deirín dé,
--Ach codail go sámh go fáinne an lae!


I. The nightjar [lit. little goat of the night!] is abroad in the heather, The brown bittern speaks in the reeds.
II. Cows will go west at dawn of day, And my child will go to mind them in the pasture.
III. The moon will rise and the sun will set, Cows will return at close of day.
IV. I shall let my child go picking blackberries – but sleep soundly till daybreak!

Singable translation by Donal O'Sullivan:

Derreen day, derreen day,
The nightjar calls upon the heath.
Derreen day, derreen day,
The bittern booms the reeds beneath.

…Cows will go west at dawn of day, …
My darling will watch them lest they stray.

…The new moon greets the setting sun's ray, …
Homeward the cows will wend their way.

…I'll let my darling go gathering may, …
If he sleeps soundly till dawn of day.


The following verses and tune are in Mícheál Ó hEidhin, Cas Amhrán (first published 1975, still available from Cló Iar-Chonnachta
This book has songs and their airs only, no background info. or translations.

DEIRÍN DÉ, DEIRÍN DÉ

Déirín Dé, Déirín Dé,
Tá'n gabhar donn ag labhairt sa fhraoch,
Déirín Dé, Déirín Dé,
Tá na lachain a' screadach sa fhéith.

Déirín Dé, Déirín Dé,
Gabhfaidh ba siar le héirí an lae
Déirín Dé, Déirín Dé,
Is rachaidh mo leanbh á bhfeighilt ar féar

Éireoidh gealach is rachaidh grian fé ...
'S tusa mo leanbh 's mo chuid den saol...

Ligfead mo leanbh a' piocadh sméar ...
Codladh go sámh go sámh go fáinn' an lae.

(1.The brown goat is 'speaking' in the heather, the ducks are screeching in the reeds 2. The cattle will go west at daybreak, and my child will look after them on the grass 3. The moon will rise and the sun will set, you are my child and my share of the world 4. I will let my child pick blackberries, Sleep soundly until the dawn [literally, ring of the day])

Most of the verses are common to both versions, and I don't see why you can't combine them as you wish, or add lines as appropriate. For instance in May, the cuckoo calls, and the child could truly gather may (hawthorn blossoms), as in O'Sullivan's poetic translation. The grammar should be consistent in any compilation version, however: sa fhraoch & sa(n) fhéith are Ulster equivalents for san bhfraoch & san bhféith.