These are 5 yen coins. A 5 yen coin is the only Japanese coin which does not carry any Hindu Arabic numeral.
Each is worth a bit over 5 Australian cents, so not much value, but for Japanese people it has a special meaning.
五円(ごえん, 5 yen) has the same sound as ご縁 (good relationship), so many Japanese people keep a 5 yen coin of their birth year in their coin purse all the time so that they will have a good relationship with money.
At the bottom of the right side coin says 平成十六年. 平成 (Heisei) is the name of the current emperor’s era. 十六 is "16" and 年 (nen) means “year,” so this coin was made in the 16th year of the current emperor’s reign. The current emperor was crowned in 1989, so 平成十六年 is 2004.
The current emperor is turning 84 in December and it has been decided that he is going to retire next year. We are yet to know what the next emperor’s era is going to be called. There will be an announcement soon!
If you want to know what your birth year looks like in Kanji, please email me at easyjapanesee@gmail.com, I will write back to you.