Due to your location, you are going to have to be extra careful in your coin purchases. Many
US coins (silver dollars especially) have been copied in China. This is legal in China as it is considered "art". Unfortunately, these "coins" are then being sold as genuine. You will see these on
ebay all the time and I'm sure you see them quite often where you are.
If you purchase on the internet, you also need to be cautious. Many of these fantasy pieces have been sold to US buyers as genuine coins and, in turn, are now being sold out of the US (and other countries).
In discussing the coins that you already have, it is going to be very important for you to post pictures. We have a member here who not only is an expert on identifying counterfeits, he often can tell you exactly when and where they were made.
Keep in mind that some of these are not modern Chinese fantasy pieces. There were also contemporary counterfeits that actually have some value to them.