Unlike Trinity Sunday, which is perhaps the last-instituted feast to have Offertory verses, Corpus Christi, having been established a few centuries later, has none. However, the Offertory of Corpus Christi, "Sacerdotes Domini" (based on Leviticus 21:6), is set to the same melody as the Offertory of Pentecost "Confirma hoc", which itself has three verses… so it seemed appropriate to try to find suitable texts from Leviticus to fit to the melody of those three. I assume that, technically speaking, once the Offertory itself is sung, anything following it is allowed if it is in Latin and has an appropriate text and tune, as is true of any Offertory motet.

A few phrases from Leviticus 21:7-8 seem appropriate to constitute a first Offertory verse, but the rest of chapter 21 far less so (e.g. "They shall not take to wife a harlot or a vile prostitute... If the daughter of a priest be taken in whoredom, and dishonour the name of her father, she shall be burnt with fire.") For this reason, I chose three other texts from elsewhere in that book to make up two more verses (Lev. 3:9 and 1:4; 6:18).

These three verses can then be fitted to the melody of the Pentecost Offertory verses (the first to the third, the second to the second, and the third to the first); and the repetend "Et non polluent" begins in the same place as that of the original melody in the Pentecost Offertory (at "Tibi offerent"):

Sacerdótes Dómini incénsum et panes ófferunt Deo: et ideo sancti erunt Deo suo, * Et non pólluent nomen ejus, allelúja.
V. 1. Quia consecráti sunt Deo suo, et panes propositiónis ófferunt, sint ergo sancti. * Et non pólluent nomen ejus, allelúja.
V. 2. Et ófferent sacrifícium Dómino, et acceptábile erit Deo. * Et non pólluent nomen ejus, allelúja.
V. 3. Sempitérnum erit in generatiónibus vestris de sacrifíciis Dómini: omnis qui tetígerit illa, sanctificábitur. * Et non pólluent nomen ejus, allelúja.

The priests of the Lord offer incense and bread to God: and therefore they shall be holy to their God, * And they shall not profane his name, alleluia.
V. 1. Because they are consecrated to their God, and offer the loaves of proposition, let them therefore be holy. * And they shall not profane his name, alleluia.
V. 2. And they shall offer a sacrifice to the Lord, and it shall be acceptable to God. * And they shall not profane his name, alleluia.
V. 3. It shall be everlasting in your generations concerning the sacrifices of the Lord: Every one that toucheth them shall be sanctified. * And they shall not profane his name, alleluia.

Here is the setting - note that the full and half bars are obviously in the wrong places for the new text, but I deliberately left them in the same places as they were in the original, rather than try to adjust them. It seems to me that, as the Church set the Corpus Christi Offertory to the melody of the Pentecost Offertory, without more than a few tiny adjustments to the new text, the same ought be appropriate regarding new verses.