Is there a reason you think it is clad? I found one of these metal detecting and mine was from about 1780-1820 or so, can't remember the exact dates. Mine was found at a really old homestead in misouri and the most recent coins found in the area were WWII but the home was built about 1830. I assume the chinese coin was a souvenir brought home from WWI or WWII. They don't change the years on them for each year, just the name of the ruler or dynasty or whatever he is and you can age it by when he reigned.
Yours may be a reproduction, especially if you think it is a lighter metal such as pewter, the originals are bronze or brass. You have to look closely and compare the chinese writing to find the same coin. Here is one such reproduction....
http://www.magictails.com/images/taosim_i-ching_images/i-ching_books_coins/i-ching_coins_bronze_1.jpg
http://www.magictails.com/library/taosim_i-ching_coin_bronze_1_inch.html
Unless you found it in the ground with 200+ year old coins in the area, I would be suspictious of it being a reproduction. Some repro's are bronze as well. These are not very rare in China, they have coins hoarded from 2000 years where as the USA only has coins for the past 300 years.