Pica Cravings

So I'm 31 weeks as of today and for the past few weeks I've been having pica cravings(craving things for non human consumption), these include gravel, Windex, cat food( I don't even have a cat nor do I like them), bleach, Lysol wipes, dry erase markers and the most common one CHALK, does anybody know what I should do to satisfy these cravings other than consuming this stuff. BTW I've let my OBGYN know about it and I have to get iron transfusions because of it but I really need something to snack on other than these things.