The first musical settings were based upon Gitanjali and The Gardener, Tagore's first texts in English. Whether a hymn to nature, to a deity, or to a lover, these poems are representing song-offerings impossible not to use. Composers started using other texts for settings too, like The Cresent Moon and Fruit-Gathering, when these became available in translation.

As translations in many other languages followed rapidly after the English version, musical settings were composed in many different languages. An impression can be found on's Tagore page.

What I am trying to accomplish is identifying these compositions, and linking individual poems to settings. On the Settings-page there are 383 settings from Gitanjali, 309 from The Gardener, and for instance from The Crescent Moon 47.

Besides poems, also Tagore's aphorisms are widely used and set to music, especially from Stray Birds. And on this very moment Tagore's poems are being set to music, in all kinds of musical formats.

On-line texts

Many translations can be found on-line, esp. in the Gutenberg project.
Here a selection, with the abbreviation as used in the Settings-page:

Gitanjali (Gtj) - a collection of 103 poems translated from Bengali into English by Tagore himself, published in 1912. About half of these poems were originally published in 1910, in the Bengali Gitanjali. The remaining were from other collections, mainly Gitimallo, Noibeddo (1901) and Khea (1906).
Full texts: in English - Song Offerings, in German - Sangesopfer and in Spanish - Gitanjali, and in Finnish - Uhrilauluhja.
Translated in Polish as: Pieśni ofiarne, in Dutch as Wijzangen, and in Italian as: Canti di offerta.
See also the Wikipedia pages in English, and in Bangla.

The Gardener (Grd) - a collection of 85 poems, also translated by Tagore, published in 1913 in English.
Full texts: in English - The Gardener, in German - Der Gärtner, in Spanish - El Jardinero, in French - Le jardinier d'amour. Translated in Polish as Ogrodnik, and in Finnish as Puutarhuri.

Fruit-gathering (Frg) - a collection of 86 poems, translated 1916 from Bengali by Tagore.
Full texts: in English - Fruit-gathering Translated in Italian as: Il paniere di frutta

Fireflies aka Lekhan (Lek) - published bilangual by Tagore in facsimile in 1926 in Budapest, 256 epigrams and short verses. A bit like haikus, as Bangla is able to express ideas with a minimum of words, where Western languages need much more. An earlier set of epigrams was published in 1899 as Kanika, a third, posthumus bundle in 1945 as Sphulinga (Sphul).
Full text: in English - Fireflies

Straybirds (Sb) - translated 1916 from the Bengali by Tagore
Full text: in English - Straybirds

Lover's Gift - (Gift) - 60 poems published together with Crossing in 1918
Full text in English is available via Google Books
(English Writings of Rabindranath Tagore: Poems - Sahitya Akademi, 2004 ISBN 8126012951)

The Fugitive (Fug) - 1921
Full text: The Fugitive and Other Poems

Songs of Kabir (Kb) - 100 poems from Kabir, a 15th century poet, translated by Tagore and published in 1915
Full text: Songs of Kabir

Other texts:
Visarjan (The Sacrifice) - published 1890
Raja (The King of the Dark Chamber) - published 1910
Dak Ghar (The Post Office) - published 1912
The Crescent Moon (CM) - published 1913, on-line text here
Sadhana: The Realisation of Life - published 1913
The Hungry Stones and other stories - published 1916
Ghare Baire (The Home and The World) - published 1916
The Harvest (Har) - text in Spanish: La Cosecha
The Child (Child)
Land of Cards (Tasher Desh) - a dance drama based on Alice in Wonderland
For a synopsis: Land of Cards

See also:
Google Books: Tagore's English texts
Gutenberg project on Tagore's texts
Terebess Asia Online (TAO)