For Harvest or Thanksgiving Day

Almighty God, most merciful Father,
you open your hand and satisfy the desire of every living thing.
We give you most humble and hearty thanks
that you have crowned the fields with your blessing,
and have permitted us once more
to gather in the fruits of the earth.
Bless and protect the living seed of your Word sown in our hearts,
that in the abundant fruits of righteousness
we may always present to you an acceptable thank-offering;
through your Son, Jesus Christ our Lord,
who lives and reigns with you and the Holy Spirit,
one true God, now and forever. Amen.

Source: The Lutheran Hymnary, 1913, probably from some older source. This version from Prayers from the Evangelical-Lutheran Heritage, #166.

Modified to be an offering prayer for any occasion:

Almighty God, most merciful Father, you open your hand and satisfy the desire of every living thing. We give you thanks for crowning our lives with your blessing. Bless and protect the living seed of your Word sown in our hearts, that we may always present to you an acceptable thank offering with the first fruits of our labor; through your Son, Jesus Christ our Lord. Amen.