It says "He m., 1309, Margaret, da. of Gilbert (de Clare)..." As
everyone who followed the Amie debate could probably say, the marriage
date is incorrect.
Apparently it was the chronicler Johannis de Trokelowe (the one who
said Piers and Edward II were "coetani" - contemporaries - close in
age) who first got the date wrong, placing the marriage of Piers and
Margaret in 1309, after his return from Ireland. Whether Trokelowe
was CP's source is not known - CP doesn't cite its source for the
marriage date.
But what is known is that Piers and Margaret were married at
Berkhampstead on All Saints' Day (1 November) 1307. Berkhampstead was
a smart choice - it had been the chief administrative seat of the two
previous earls of Cornwall, Richard, King of the Romans, and his son
Edmund. The proof is the chronicle of Walter of Guisborough, the
Annales Paulini chronicle, plus a contemporary royal household
document.
PRO E 101/373/15 fo.22 "Primo die novembris, videlicet in festo Omnium
Sanctorum, in denariis liberatis ipsi regi apud Berkhamstede ad
nupcias domini P. de Gavaston' et filie comitus Glouc' videlicet
projectis ibidem ad hostium ecclesie ultra capita dictorum domini
Petri et uxoris sue eodem die in introitu eorumdem in ecclesia
predicta, per manus Willelmi de Boudon' liberantis denarios eidem regi
apud Berkhamstede, vij li. x s. vj d." [As transcribed by Pierre
Chaplais in his 1994 biography of Gaveston, pg. 34.]
The above describes how f7 10s. worth of pennies were thrown over the
heads of Piers and Margaret as they were about to enter the church.
Since pennies are heavier than rice, I hope they were wearing hats!
Cheers, -------Brad