The Nine Maidens was created in 1985.
Maidens IV was created in 2003.
The Iron Maidens was created in 2001.
Star Maidens was created on 1976-09-01.
Maidens' Vow was created on 2006-08-28.
Our Modern Maidens was created on 1929-08-24.
Maidens railway station was created in 1906.
The Three Witch Maidens was created in 1972.
Roller Maidens from Outer Space was created in 1974.
Fire Maidens from Outer Space was created on 1956-09-06.
Seven maidens (girls) and seven youths (boys) were to be sent to Crete to feed the Minotaur every nine years.
Heimdall, son of Odin and the nine daughters of Aegir and Ran, called the Billow Maidens or Waves; was guardian of the Bifröst, the Rainbow Bridge which is the closest to come to a "goddess of the rainbow"; either the Bifröst/Heimdall, or the nine Wave/Billow Maidens.
There is no specific collective noun for maidens, in which case you use a collective noun that is suitable for the situation; for example a mildness of maidens, a mob of maidens, a mayhem of maidens, etc.