You might be mistaken. I have never heard of a 'Psalm Sunday' - but there is a 'Palm Sunday' which is the Sunday before Easter Sunday. It is so called because the Gospel read that day in Christian churches concerns itself with how Jesus rode into Jerusalem and was greeted by people laying palm-leaves in his path.
Psalm 89.1-18
The psalm for the Mass on Corpus Christi (Sunday, 2 June 2013) is Psalm 110, verses 1-4 in the new numbering (it would be psalm 109 in the Vulgate).
On all Sundays and Solemnities (Christmas, All Saints, Immaculate Conception, Assumption, etc.) there are three (well, four if you count the psalm), usually an Old Testament reading, a psalm, a New Testament reading, and the Gospel. Weekday Masses only have one reading, the psalm, and the Gospel, there is no second reading on a non-solemnity.
Psalm 89.1-18
Read Psalm 104:6-9
Sunday Funday happened in 1995.
Sunday bloody Sunday happened on January 30th 1972
It was a Sunday.
ESPN Sunday Night NFL happened in 1994.
Easter Sunday Raid happened on 1942-04-09.
The Stono Rebellion happened September 9, 1739, a Sunday Morning. The Stono Rebellion happened September 9, 1739, a Sunday Morning.