Find a resource that specializes in mushrooms in the area. Several websites specialize in the mushrooms of British Columbia, and books are available as well. Review these resources and narrow down the mushroom types that grow in your local region.
Study the mushrooms you find and take note of their height, color and texture. Look on the top and bottom of the mushroom, and also consider where they were growing. Compare this to the mushroom varieties in your guide.
Contact local mushroom growers, gatherers or buyers to have an expert look at the mushrooms you have collected. This is particularly important if you are going to consume the mushroom, and if you are a novice at mushroom collecting.