By complete dumb luck I got an R99 Magical Mushroom from the Magic Box... Now I'm completely lost though, and I have no clue which shops to restock in. This part isn't exactly bragging/complaining, but I don't know where else to put it. Any suggestions for which shops I should restock in?

book nook is always good at the moment with the reading drive going on. suboutique in centropolis if you have enough sp so far ;) and if you're lucky, you may snatch a ornate pitcher in seedlings

Food also sells pretty well, as a lot of quests ask for it.

I've been in Book Nook most of this morning, gotten a few good items. I'll check out Suboutique, Seedlings and Food though, thanks :)