Hello all- I have been researching this with great enthusiasm and have found some clues but I am not an expert on dreams nor Celtic symbolism-but rapidly learning.
I say hello again to Godot-we seem to share a great deal of the same interests and lo and behold here you are!
Here are some things which I have found-perhaps you can put them together to some meaning all taken from Celtic /Irish lore (these are all VERY powerful Irish symbols!)
The LADY is, I agree probably the Morrigan-or possibly one of her aspects the Badb?-whose favourite disguise is that of the Raven or Crow (Hoodie)
The Raven / Crow both have close to the same meaning-However one site I visted indicates the Crow/Hoodie is a harbinger of death and the Raven is a favourable death (what exactly that means is not explained-does that mean the death of an enemy, perhaps-or perhaps it represents the death of an outmoded way of thinking?)
I could find no reference to a burning silver cup or chalice as far as Celtic mythology or related lore however SILVER is much more valuable than gold, and relates to Authority
A chalice can represent the Feminine principle of Creation-although the Morrigan and her aspects are considered Warrior Goddesses (my kind of gals!) and are most often associated with death / destruction-so how that would fit is unclear
Fire represents belonging to a Tribe (Clan?) and can also represent illumination as well as power / strength
Acorns are Druidic symbols and can mean patience or the fruition of a long hard labor-and can also symbolize wisdom, truth, strength, birth or fruitfulness
Water (body of water) Means crossing of borders /realms
I could find no specifics on rain or gold coins-only that gold was less important (magically) than silver-nor any references to rain but did find a reference to "electric clouds" (nel in Gaelic?) which refers to the Brain! Perhaps the flash of light you see is not so much related to rain as to lightening-electrified clouds? Perhaps signifying a elevation in Brain activity?
This is a very potent message-one that I don't think anyone but someone of Irish descent could possibly have-all of these symbols are uniquely Celtic-especially the Morrigan. Curiously I could find no description of her other than to say she likes to appear as a Raven /Crow-no physical description as to hair color or eyes (She is one of the Tuatha De Danann-and a Warrior Goddess was all along with her genealogy) nor could I find any reference to her as far as a flaming silver chalice /cup, gold coins or acorns.
It is also curious that she speaks the words-Do not be afraid just as you awaken. If you have the dream frequently you might try lucid dreaming-in which you are in control of your dream-and see if you can coax her into explaining what she means.
Perhaps the chalice is a symbol of her authority, the flames indicate your entry into an elite group or "tribe" (the Cassiopean community?) or perhaps illumination- the flash of light (electric clouds?) indicate the elevation of your intellect /inner self-and the tossing of the acorn-representing your hard work /labor, patience and wisdom is about to pay off by carrying you into a higher realm (crossing a border) or you are successfully breaking out of an outmoded paradigm of thinking and are crossing into a new realm of thought?
Then again - and I am really not well enough versed in any of this to say-these could very well be screen memories for abduction scenarios? It would be just like our hyperdimensional friends to pull some very powerful, archetypical symbols like this out of their bag of tricks to cover up their hijinx-especially the "Don't be afraid!" part-that sounds SOOOO 4th D oriented...maybe EsoQuest or someone with more experience could comment on this?
I haven't answered your question as to what this dream signifies-but with a bunch of people working on it maybe something will clarify it. I'd be real curious to find out what someone that is experienced in interpreting dreams might make of it.
I found a lot of info and fantastic links at this site:
http://www.imbas.org