Mauricio,
1- It is more likely to hear from some archives in Italy if the request is made by an individual associated with an university, a museum, or another archive. If possible go that root.
2- As for San Gimignano - it's coat of arms shows a rampant lion, holding a blue sphere with 3 fleurs de lys (I guess in gold -can't see well). The city's banner is red and yellow. The various "quartieri" also have their own banners which are carried and paraded during festivals, generally by important citizens.
A famous one : "Ferie delle Messi" - a medieval - lasts 3 days, see:
<
http://www.comune.sangimignano.com/index.htm>
you can see the "gonfalonieri" carrying the "gonfalone=standard; banner".
For more info. on the history check:
<
http://www.comune.sangimignano.siena.it>
Can't tell you of the emotion of seeing it for the first time, with the sun
setting on all golden towers!
I will try to check some of my notes. Let you know if any luck!
Aether

"Fiori di grano.
Amici piu' di prima saremo;
Amici piu' di prima da lontano".