Here are the lyrics from Pádraigín Ní Uallacháin's album, A Stór 'S A Stóirín - GAEL LINN FONN CD001

AMHRÁN NA BEALTAINE

Bábóg na Bealtaine, maighdean an tSamhraidh,
Suas gach cnoc is síos gach gleann
Cailíní maiseacha bángheala gléigeal
Thugamar féin an Samhradh linn

chorus/curfá
Samhradh buí ó luí na gréine
Thugamar féin an samhradh linn
Ó bhaile go baile 's 'na baile 'na dhiaidh sin
Thugamar féin an samhradh linn

Tá nead ag an ghiorria ar imeall na haille,
Is nead ag an chorr éisc i ngéagaibh an chrainn,
Tá'n chuach 's na héanlaith a' seinm le pléisiúr,
Thugamar féin an samhradh linn.

Tá an fhuiseog a' seinm 's a' luascadh sna spéartha
Beacha is cuileoga is bláth ar na crainn
Tá míl ar na cuiseoga 's coilm a' beiceadh,
Thugamar fin an samhradh linn.

The first verse is as the third verse from Belfast musicians Ceoltóirí Loch Lao, which is given at the beginning of this thread. The line "Ó bhaile go baile 's 'na baile 'na dhiaidh sin" in the chorus says from town to town to the town after that, implying a processional.
The other verses are about nature, the hare and the heron nesting, the cuckoo singing, the lark twirling in the air as it sings, bees and flies on the tree, the dove cooing.

Last year, Pádraigín issued a CD titled "An Dealg ir" (the golden thorn) based on her intensive research into the Irish-language songs of south-east Ulster (she lives in County Armagh). The album includes 2 songs for May Day; I've posted "Amhrá na Craoibhe" on another thread. In "An Dealg ir", "Thugamar Féin an Samhradh Linn" begins thus:

Samhradh buí 'na luí ins na léanaí
Thugamar féin an samhradh linn.
Samhradh buí earrach 'us geimhreadh,
Thugamar féin an samhradh linn.
Cailíní óga, mómhar sciamhach,
Thugamar féin an samhradh linn.
Buachaillí glice, teann is lúfar,
Thugamar féin an samhradh linn.

It then continues much as in Pádraigín's earlier recording, though the lines are sung in somewhat different order and the chorus is not sung as a chorus but as a final verse with the third line "Ó bhaile go baile ag ságradh le pléisiúr" (from town to town cavorting pleasurably). The tune is different again, as research uncovered a tune from a wax cylinder recording made by Luke Donellan around 1900 and transcribed by folklorist and musician Séamus Ennis in the 1940s. The words are drawn from a number of versions of the song noted in the area.

Before an older local air was rediscovered, both Pádraigín and Eithne Ní Uallacháin had composed their own airs for their version of Thugamar Féin an Samhradh Linn. Eithne's recording is on Brigid's Kiss (LUG CD 961).

From notes for An Dealg Ó:
"[this song] is a version of one of the oldest songs in the Irish tradition. The earliest version appears c. 1745 though undoubtedly is is much older. It was sung then at the landing of James, Duke of Ormond, when the people welcomed him with singing, dancing and the strewing of flowers. It was sung traditionally at Maytime in south-east Ulster by groups of young men and women going from house to house welcoming in the summer while carrying the May branch or 'Doll' [Babág or Brídeog] or 'Garland', which in this context signifies summer and fertility."