Jacet granum
Anonymous (?Benet):
Gloria   Sanctus
Edition: Gareth Curtis, ed., Fifteenth-Century Liturgical Music IV: Early Masses and Mass-Pairs, Early English Church Music, 42 (London: Stainer and Bell for The British Academy, 2001), 56-74.

Je n’ay dueul
Antoine Brumel:
Kyrie   Gloria   Credo   Sanctus   Agnus Dei
Edition:  Antonius Brumel, Opera omnia, ed. Barton Hudson, 6 vols., Corpus mensurabilis musicae, 5 (n.p.: American Institute of Musicology, 1969-72), 1: 1-19.
Johannes Ghiselin - Verbonnet:
Kyrie   Gloria   Credo   Sanctus   Agnus Dei
Edition:  Johannes Ghiselin-Verbonnet, Opera omnia, ed. Clytus Gottwald, 4 vols., Corpus Mensurabilis Musicae, 23 (American Institute of Musicology, 1961-68), 3: 35-65.

Je ne demande
Anonymous:
Kyrie   Gloria   Credo   Sanctus   Agnus Dei
Source: VatS 51, fols. 165v-176r.
Alexander Agricola:
Kyrie   Gloria   Credo   Sanctus   Agnus Dei
Edition: Alexander Agricola, Opera omnia, ed. Edward R. Lerner, 5 vols., Corpus mensurabilis musicae, 22 ([s.l.:] American Institute of Musicology, 1961-1970), 1: 34-65.
Jacob Obrecht:
Kyrie   Gloria   Credo   Sanctus   Agnus Dei
Edition: Jacob Obrecht, New Obrecht Edition, gen.ed. C. J. Maas, 18 vols. (Utrecht: Vereniging voor Nederlandse Muziekgeschiedenis, 1983-1999), 5: 35-84.

Je ne fay plus
Heinrich Isaac:
Kyrie   Gloria   Credo   Sanctus  
Source: MunBS 3154, fols. 380r-388r (c.1506-7).
Edition: Thomas L. Noblitt, ed., Der Kodex des Magister Nicolaus Leopold: Staatsbibliothek München Mus. ms. 3154, 4 vols., Das Erbe deutscher Musik, 80-83 (Kassel and New York: Bärenreiter, 1987- ), 4: 45-71.
The model was identified, and Isaac’s authorship of the Mass established, by Adam Knight Gilbert.

Je ne seray plus vert vestus
Jacob Obrecht:
Kyrie   Gloria   Credo   Sanctus   Agnus Dei
Edition: Jacob Obrecht, New Obrecht Edition, gen.ed. C. J. Maas, 18 vols. (Utrecht: Vereniging voor Nederlandse Muziekgeschiedenis, 1983-1999), 14: 1-21.

Je ne vis onques la pareille
Alexander Agricola:
Credo I 
Credo II
Edition: Alexander Agricola, Opera omnia, ed. Edward R. Lerner, 5 vols., Corpus mensurabilis musicae, 22 ([s.l.:] American Institute of Musicology, 1961-1970), 2: 94-113.

Jesu Christe Fili Dei
John Dunstable:
Gloria   Credo
Edition: John Dunstable, Complete Works, 2nd edn., ed. Manfred Bukofzer et al., Musica Britannica, 8 (London: Stainer and Bell, 1970), 35-40.

Je suis en la mer
Guillaume Faugues:
Kyrie   Gloria   Credo   Sanctus   Agnus Dei
Source: ModE M.I.13 fols. 192v-207r.
Edition:  Guillaume Faugues, Collected Works, ed. George C. Schuetze (New York: Institute of Mediaeval Music, 1960), 147-78.

Jesus autem transiens
Firminus Caron:
Kyrie   Gloria   Credo   Sanctus   Agnus Dei
Edition:  James Thomson, ed., Les oeuvres complètes de Philippe (?) Caron, 2 vols. (Brooklyn, N.Y.: The Institute of Mediaeval Music, 1976), 1: 67-99.
Alternative recording of this Mass on the Caron Website.

Jocundare
Johannes Ockeghem (lost):
Osanna (excerpt)
Excerpt from the Osanna of Missa Iocundare by Johannes Ockeghem. Cited in Ludovico Zacconi, Prattica di musica utile (Venice: Bartolomeo Carampello, 1596), fol. 190v.

Joye me fuit
Johannes Ghiselin-Verbonnet:
Sanctus   Agnus Dei
Edition:  Johannes Ghiselin-Verbonnet, Opera omnia, ed. Clytus Gottwald, 4 vols., Corpus Mensurabilis Musicae, 23 (American Institute of Musicology, 1961-68), 4: 40-50.