I've hosted and danced in one yes. It is based on most of the beliefs but because outsiders are allowed, most of our rituals are not used due to the secrecy of them.
Native Drum circles are also open to the public. You should check if there are any in your area. They even offer "healing" drum circles.
What area were you in when you attended? Mine was in Michigan with the Ojibwe (Chippewa) and the South Eastern tribes. I loved shopping at the vendors and getting my seed beads really cheap :) They usually have teachings on beading and also some children's circles to teach about the significance of tobacco and other things.
In the culture we make our own dance regalia - it is tradition. If the children are small, sisters or mothers make them for them. Traditional Women's Dance is to honor our warriors who have gone hunting. Some women use this dance to honor fallen warriors as well. (each tribe is different) This is what I did mostly. Shown here
http://www.youtube.com/watch?v=myrgXHao3V0
The Women's Traditional Dance is the very oldest form of dance for ladies. Females of all ages are seen dancing this very regal and proud style. Pride of heritage, culture, and family can be seen in the faces and demeanor of these well-respected dancers. In fact, when performing this style in competitions, judges watch the ladies to see if the required dignity is retained all throughout the dance.
When moving in the Circle, there are Northern and Southern ways of dancing Women's Traditional. Northern style is danced by remaining in one spot, lightly bouncing in rhythm with the drum. Southern style has the women slowly and gracefully walking around the Circle in time with the drum, gently stepping toe-heel, toe-heel with the feet appearing to "walk on clouds". Both styles carry a fringed shawl folded over their bent left arm, a purse in their left hand, and a feather fan, usually eagle or hawk, in their right hand.
The women hold themselves tall and proud, their bodies straight. The fringe on the shawl is to sway naturally with the movements of the women's feet, not from upper body bending or swinging. The fan is raised in salute when the women hear the drum giving honor beats.
Both cloth and buckskin dancers wear a leather conch belt from which they hang a knife in its case and a tobacco pouch situated at the sides or back of the waist. Each style also wears a breastplate made from bone pipe and glass beads that can drape to the waist (Southern) or all the way to the ankles (Northern). However cloth dancers typically wear their breastplates over the front and back, unlike the buckskin dancers who wear just a front-sided style. At the neck, the ladies wear either a scarf or a choker. Other jewelry is optional and usually is in designs and colors that have either personal, tribal, or family significance. The hair can be worn pretty much however the woman desires from loose and flowing to braided.
Some dancers will weave ribbons in their braids or wear beaded barrettes and pieces of fur attached to their hair as well. Also, although most dancers wear a single feather (usually eagle or hawk) in their hair, some have been seen wearing several feathers.
http://www.youtube.com/watch?v=pE53kqE45sQ Here is a youtube of fancy shawl dancers
Women’s Fancy Shawl Dance
During the early 1900’s Native American women began to replace their blankets and buffalo robes with colorful shawls for dancing. Some say that as the women produced more intricate designs on their shawls they were more likely to dance fancier footsteps during dances to show off their shawls. This in turn gave rise to the Women’s Fancy Shawl Dance. Most of the dancers will wear a cloth, knee-length skirt, beaded moccasins and leggings, a traditional shirt with trade silver, topped off by a bright colored shawl. The style of the dance is very ostentatious. Flashy footwork and spinning with much more movement than traditional dancing are a part of the Women’s Fancy Shawl Dance.