Souvenir Trading

I’ve been trading items for souvenirs with locals I’ve come across in the streets of the past few places I’ve visited and I want to continue

Would it be considered inappropriate or taboo in Japan to ask a stranger if they’d like to trade for something ? If not, are there any items that are especially “trade worthy” or appreciated? I’ll be spending three weeks in Tokyo, Nagoya, and Osaka.

Things I have used to trade:
American city or state patches, hats , American regional snacks, cowboy belt buckles, sports t shirts , backpacks/Bags