I don't think there's anything wrong with turning over one mushroom to see what's on the underside. You're not destroying the fungus since the perennial mycelium is intact in the soil. If you do remove a mushroom, do it carefully to make sure you get it out intact. You will need to get below the base of the stem (e.g with a finger or nearby stick) and ease the entire mushroom out. Don't just pull on the cap, since you may then damage the stem and lose some useful identifying features.