I've found and eaten one of these, and honestly it wasn't amazing. Regular store mushrooms, agaricus bisporus, are actually better IMO. Although looks like she cooked it way better than I did.
Sliced, breaded, and fried puffball makes an excellent fried chicken alternative for food like sandwiches or pasta dishes. I'm always a fan of puffball parm.
Can you keep them fresh for a whole week after harvesting AND cutting them? Something like champignons seem to just mold away after a couple days already.
Some mushrooms cover themselves in a little mold which is still safe to eat. If it's white and looks a little fluffy, you don't need to throw them away yet. Specifically for champignons, that is. Not sure about other mushrooms
We used to get these puffball mushrooms in our woods growing up. Some of them got huge (but never 5kg huge), but we never harvested and ate them. They are so alien looking!