Printable copies of the music and propers for various Masses have been made available here; they were originally developed for John Fisher House, the Cambridge Chaplaincy. They include some interesting features, such as the Offertory Verses. These verses, to which the Offertory Antiphon is the antiphon, are theologically rich and musically and poetically very interesting. The Schola Abelis in Oxford frequently sings them; they are sung by a cantor, and at the end of verses the full schola repeats all or part of the antiphon. They are not for the faint-hearted, however, as they are difficult. They are optional in the Extraordinary Form, which is to say (as far as I can work it out) they are not in the Missal, so there is no obligation to sing them, but as it is permissible (and there is usually time) to sing extra things at the Offertory, nothing more appropriate can be imagined than the original verses which go with the Offertory Antiphon in the medieval manuscripts (this was made explicit bty Musica Sacra in 1958). An edition of the music for these verses, produced originally in 1935, is available on the Catholic Music Association of America site here (big pdf).
Offertory Confirma hoc, for Pentecost, with the ancient verses, sung by the Schola Abelis.
Those choirs which sing these Offertory verses may well want to provide the congregation with the text, and a translation, which is provided in these sheets.