There are 5 steps that can be followed to remove mold stains: 

1. First take the item outside, so as not to spread mold spores indoors, and brush as much of the mold off as you can.
2. Allow the item to dry in the sun for awhile, as direct sunlight can often kill many different types of mold spores.
3. After plenty of sunlight has been distributed evenly over the item, presoak it in cold water possibly with a bleach solution, color safe if it has colors in it, and then machine wash it with warm water and detergent.
4. Lemon juice and salt in cold water has also been used with colored fabrics, as well as a vinegar solution to aid in smell removal.
5. Hang the item in the sun again to dry. 

Unfortunately, mold does leave stains but by using the previous solution and washing materials in this manner, you have rid the items of mold and most likely the musty smell as well, however removing mold stains is an entirely different matter.

Note Also:

Here are a couple of ideas that I haven’t prove my self, but that may be worth trying.

• X-14 Mildew Stain Remover with Bleach will often remove the stains.
• Try mixing 2 cap fulls of Milton baby sterilizing fluid with 3-4 liters of water and soak the item over night.

Further Recommended Reading:

• How to Remove Mold and the Smell from Clothing

Joslyn from the MoldBlogger team