How to Store Fresh Mushrooms. Mushrooms can be one of the hardest vegetables to store because of how quickly they can absorb too much moisture and start to go bad. Keeping mushrooms in their original packaging for as long as possible. Mushrooms are edible fungi full of deep woodsy flavor that add depth and heartiness to dishes. There are untold varieties of edible mushrooms, but as different as their flavors are they can be treated and used in much the same way. How to Preserve Fresh Mushrooms. Cooking with fresh mushrooms adds an earthy, umami flavor to any dish! However, fresh refrigerated mushrooms tend to go bad within a week or less. You can keep and use them for longer by freezing them. Mushrooms aren’t exactly the hardiest of ingredients! Once home, they can become slimy and develop brown spots within just a few days. If we can’t use them all right away, we try to do whatever we can to eek out just a little more life from our mushrooms. Here’s how…Lots of theories seem to exist about the best way to store. Learn the best ways on how to store mushrooms including shiitake, portobello, oyster and sliced button mushrooms. Keep your mushrooms fresh with these tips! Learn how to store fresh mushrooms right and they will stay good for about a week. You can also learn about freezing and drying mushrooms. How to Store Mushrooms. These elegant vegetables are actually the fruit of underground fungi. Try not to store them for long, or you'll lose the delicate flavor. Magic mushrooms aren't something you can just go out and get whenever you please. For most drugs, as long as you know somebody who grows their own or has a good supplier, you can be fairly confident that your high of choice is going to be available when you want it.