Seriously,
Amanitas are mycorhizal, that is they need tree partners in order to fruit successfully. You can still try growing on agar, I have managed to clone A. muscaria tissue cultures from within the cap, but they are very slow growing, and you could try inoculating young pine or birch seedlings and planting them in orchards. Are you sure it is A. pantherina??? They are often confused with Amanita rubescens, the blusher which bruises pinkish. Be careful with amanitas, they're toxic.