I have found that there is a trick to this. If you have a boat requiring popcorn. Go through your neighbours' stalls first and see if you can find popcorn for sale and buy only popcorn if you can. Then completely close the app and reopen it. Head to the newspaper. You should see more ads for popcorn.
This works for most items. Obviously rarer items like metal bars or jewellry or some kinds of products are less available in the newspaper and so it is harder to manipulate it to get those items to appear.






