Mold is something every homeowner has to deal with. Sometimes it shows up in the shower, on windowsills and other places where moisture is high. It's pretty easy to remedy; just remove the source of moisture and the mold should clear up.
Mold can grow on other surfaces like fabrics. Surely you've forgotten about wet towels in your hamper, or you've left a load of clean, wet laundry in the washing machine too long and it's soured. Mold and mildew spores thrive in these dark humid environments, so it will start growing on wet clothes quickly.
Mold can also grow on clothes when they've been kept in storage. Again, if you packed your winter sweaters away in boxes and stored them where moisture is an issue — like the basement — that's the ideal environment for mold spores. Even if you zip clothes into a plastic storage bag before they've had a chance to fully dry, that too can encourage mold growth.
No matter how it happens, once mold is growing on your clothes, you have a problem. The good news is you don't have to throw your clothes away. With some persistence and quick action, you can rid those clothes of mold so they're safe to wear again.