Are you looking for edibles? Or just mushrooms in general for enjoyment? Haven't been in years, but the Chilliwack Lake area used to be great for general mushroom enjoyment. Any mature second growth or old growth forests should have an abundance of mushrooms for viewing. Can't say whether there will be an abundance of edibles. Just south of the border, many of the prime edible areas are routinely scoured by commercial pickers.
Look for well shaded forested areas with good moisture. Particularly after a good couple days of rain.