"White - double -
St. Ambrose, a doctor or teacher of the Church, was Archbishop of Milan from A.D. 374 to his death in 397. By his steadfastness he deserved well of God's people. Gentleness, meekness, humility, and obedience made him yield to every one in indifferent matters, but in those of duty he was inflexible. His writing have contributed many hymns and lecctions to the Roman Breviary. St. Ambrose died April 4, 397. -- SM "
According to the Catholic Encyclopedia, there's no direct evidence that St. Ambrose composed the liturgy of the Ambrosian Rite, but his name has been associated with it since the eight century. You can read more about the Ambrosian Rite here. And more about Ambrose himself here.
BTW, the Ambrosian Rite is a western Catholic Rite that had always maintained a procession of gifts. So no, the tradition of processing with the offertory gifts wasn't something the NO people pulled out of thin air. It's also worth mentioning that the Eastern Rites have a highly stylized form of "little entrance" where the priest and servers process with the gifts from the sanctuary, through the congregation and into the sanctuary again.