Corpus Christi has been the official patronal festival of Christ Church (William Clendenin Robertson Memorial) in Chattanooga since sometime in 1933, according to the senior warden's report at the annual parish meeting on 15 January 1934. Trinity Sunday was also designated a day for special observance as a memorial of the church’s dedication.
Corpus Christi is the Thursday after Trinity Sunday, transferrable in the Episcopal Church to the following Sunday in case of it being a patronal feast, which it is here, and in the Roman Church in places where it is not a Holy Day of Obligation.
I'm not sure when the stone cross was embedded in the mensa of the high altar, but since it is the relic of a saint, maybe we should add Callistus' feast day (14 October) as another day of special observance, like the vestry of 1933 did for Trinity Sunday.
Since the parish held its first Communion service on Ash Wednesday, that should probably be a day of special commemoration also, in addition to its other meanings.
Incidentally, I referred to the parish as I did initially because the full name of the church and parish, as consecrated in 1944 by Bishop James Maxon is "Christ Church (William Clendenin Robertson Memorial)", according to the certificate in the narthex signed by the bishop.