This kind of dream is just fascinating to me because of all of the interconnectedness between the symbols, and the repetition of the theme. Right from the beginning you are aware that healing energies are at work (golden leaves/beings, "I feel they are healers").
Gold/golden - enlightenment, divinity, the fourth and final stage in alchemical transformation (symbolized also by red).
Two (two beings/dragons) - balancing energies.
Dragons - developing self, healing, protector/guardian.
Entwined dragons/serpents - indicate a particularly healing dream.
Dragon eating your blackness - transformation of negative mental/emotional energy.
Black - negative energy, the unknown, unconscious. Alchemically, the first stage in transformation.
Bear - power, cyclic activity, Mothering energy.
Buffalo - power, primal energy, bearing of burden (in your case, emotional/sadness)
Horse - power, instinct, masculine energy.
Wings - the rising up of potential energies within self, represented by the animals which are winged, into a higher, more expanded activity.
Snake - transformation, cyclic activity, healing, danger. While one or more of these characteristics may apply in the background, I think your black water snake could represent someone in your life who is "in the perfect position to bite", an emotional position (water), perhaps a man (right side = masculine) and/or someone who is latently (seems peaceful) aggressive (right). Or it could indicate the active energies (right) of emotional (water) darkness (black) which are to be transformed (snake). I also feel that the black snake is a related representation of the blackness around or coming from you in the dragon scene. It is this energy which is in conflict with your receptive, intuitive, feeling side (left/buffalo) . As such, the single tear from your left eye is the same as the sad buffalo on your left side, an expression of pain/conflict to your emotional side. Perhaps also the release of it.
Native American dance circle - sacred circle, initiation, self development, balancing, harmonizing, healing.
Golden Sphinx - convergence of aspects of self with their divine counterparts, unity between upper and lower, initiation.
The colors - red and green are opposite colors on the primary color wheel. The gold/red and gold/green dragons sometimes "merge" … Could this represent the coming together of opposing/conflicting energies within self to consume (eat) and transform (dragons) the "blackness" around/within you into a higher level (gold)?
Besides the usual meanings, there are alchemical representations ( as Soltze suggested) for all of the colors in the dream. As I mentioned above, black represents the first stage, and gold/red represents the fourth and final stage. Green is growth and represents the second stage. The third stage, white, is conspicuously missing. As this dream seems to be using archetypal symbology, of which alchemical symbology is a part, I can't help but wonder if the missing color/stage is a suggestion as to what is needed to complete the transformation process. The white/third stage represents "new knowing". Could there be something you have yet to understand, learn, or feel as truth that, once "known", will aid in the process of transforming your "blackness" into "gold", raising you up upon the spiral of self-development?
As you can see, the symbols in this dream can be read in different ways and many different connections can be made between them. There are multiple symbols for balancing, for opposing/conflicting energies, for healing, for power, for self-development, for cyclic activity. But regardless of how you read them, a single theme emerges - transformation, healing, balancing. There are powerful forces at work within your sphere … can you feel them yet?