What should you buy when going to the USA?

so I'm going to Portland , with some of my family members, and I overheard my mom talking to my aunt that, she is going to pay her. 100$US for me. So I could choose what ever I want to buy. And I'm wanting to buy a T-shirt/Shoes. But I don't know what store there are in the USA. So could you guys tell me what store there are in the USA that is not in Canada?