We visited Oz Park (we had really great weather the entire trip), stopped at the Super Dawg Drive-In for some drinks and they had special commemorative cups! Then I bought little plush hotdogs (I already have the ceramic statue from a previous trip)
On one of our days there we stopped in a the Super H-Mart just outside of Chicago. There is a little shopping mall inside the store with a shop called Fancy Pencil Land. I got some really cute stationary & stickers, and these amazing South Korean boy band Exo-K socks. I was getting some terrible blisters from all the walking/the shoes I brought so these did the trick.
There was also a little bakery called Migahodo in the shops area that smelled so amazing. They make little walnut shaped cakes on the spot and you can watch them being made. Each cake is filled with red bean paste and a walnut, and are served hot.