The Festival of the Blessed Virgin Mary may, for pastoral reasons, be observed on 8 September instead of 15 August.
If it is observed on 8 September then the Collect, Post Communion and Lectionary for 15 August replace those for 8 September.
The Birth of the Blessed Virgin Mary

http://almanac.oremus.org/2021-09-08

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Exciting Holiness
Micah 5.2-4
Canticle: Judith 16.13-16
Romans 8.28-30
Matthew 1.[1-16] 18-23

Holy Communion
Colossians 3.1-11
Psalm 15
Luke 6.20-26

Morning Prayer
Psalm 119.1-32
Wisdom 3.1-9 or
1 Chronicles 15.1-16.3
Mark 10.17-31

Evening Prayer
Psalms 11, 12, 13
1 Kings 3
Acts 14.8-end

Additional Weekday Lectionary
Hosea 11.1-11
1 John 4.9-end

Collect

Almighty and everlasting God,
who stooped to raise fallen humanity
through the child-bearing of blessed Mary:
grant that we, who have seen your glory
revealed in our human nature
and your love made perfect in our weakness,
may daily be renewed in your image
and conformed to the pattern of your Son,
Jesus Christ our Lord,
who is alive and reigns with you,
in the unity of the Holy Spirit,
one God, now and for ever.

Post Communion

God most high,
whose handmaid bore the Word made flesh:
we thank you that in this sacrament of our redemption
you visit us with your Holy Spirit
and overshadow us by your power;
strengthen us to walk with Mary the joyful path of obedience
and so to bring forth the fruits of holiness;
through Jesus Christ our Lord.

BCP Collect

O merciful God, hear the prayers of thy servants who commemorate the Nativity of the Mother of the Lord; and grant that by the incarnation of thy dear Son we may indeed be made nigh unto him; who liveth and reigneth with thee and the Holy Ghost, one God, world without end.