If you pause on the store screen that shows all the all the stores there will be an image that fades in and out on the chip store. To be honest it's hard to make out what the actual items are from there. I believe they also show up in the rewards list.
I read that these rewards will be available until June 3rd, like only for 3 days? I thought you guys release the monthly rewards for like a whole month and move on to the next? That shouldn't be right for a deadline!