Cravings

So I've been TTC for quite some time and have PCOS. I've been on metformin to help with this however lately I've stopped stressing about it and just let nature take its course. I've been having pregnancy symptoms but I've just chalked it up to my mind playing tricks on me. One symptom I'm having that I've never had before though is CRAVING peanut butter. However - I hate peanut butter. The other night I just had to have it to the point that I raided my home for any sign of anything with peanut butter (which of course I didn't have) and I eventually settled for wow butter (peanut free alternative peanut butter) that I'm pretty sure was expired that I'd never dream of even trying before this craving. Has anyone else had cravings as one of their key pregnancy symptoms and if not what could be causing this weird craving?!