I am not a shaman myself, but am fascinated with reading, studying and trying out some of the shamanic ways. I've also taken a few classes in this field too. I do have a few different shamanic crystals myself, lets see which ones I can recall!
I know there is one crystal called "The Shaman's Stone", but I can't recall if it is one I have purchased. I know its one I'd like to have--but I have many crystals and sadly, not all are labeled (eek!) and I forget which ones are what if they don't have a label on them now.
At any rate, "The Shaman's Stone" is a protective crystal and is great especially to protect yourself from any psychic attacks or when you are doing Shamanic Journeys, etc.
The Spirit Quartz is a recent purchase for me, and it is suppose to be helpful in protecting the shaman as well. It is a crystal that will change negative energy into positive energy, so this is how it protects you. It works by providing a shield around your aura and nothing can penetrate that protective shield. It is therefore good for journeying, or when you are in the company of some negative energies/psychic-vampires. I have read that this is also a great crystal to use in group meditations, so this may be JUST the crystal for you in your upcoming June class! It could extend its properties to all involved in the class. I know it comes in various colors--and I'm not sure if the coloring makes a difference in the properties extended to the beholder--so you may want to double check on that.
A Chevron Amethyst is another crystal that I recently purchased. It is a good third-eye crystal and is a good crystal for journeying and keeping focused as well. It is also a great psychic crystal. The one I have is a tower crystal, about 3/4" to 1" tall and I have recently been using it in my crystal grids.
I hope after your class in June, you will come back and share with us your experiences during that class. Good luck and I hope the class is very helpful for you! Looking forward to hearing about your experience.