i found it while walking along a river bank at Malacca , Malaysia. if it is valuable, how much it cost?
It's very difficult to see details of your coins due to the lack of contrast in your pictures. However, the round one may be a 1/4¢ issue of Sultan Zainal Abidin III, who ruled Trengganu, a state on the northeast coast of the Maylay Peninsula in the South China Sea, dated AH1322 (CE1907). Identified as KM#17 in the Standard Catalog of World Coins, it is struck on tin, and smaller than 22mm. The catalog lists it as "rare", so if genuine it is probably worth >$50, perhaps quite a bit more to a serious collector of early Maylay Peninsula coinage. The six-sided one doesn't resemble anything shown in the catalog for that part of the world.
The round coin is a 1/4 ghirsh from the United Kingdoms of Saudi Arabia, dated AH 1356 (1937 AD). Composition copper-nickel. There are plain and reeded edge varieties. The language on the coin is arabic. The Burmese coin is as stated by rdwarrior.
the six-sided is an old burmese coin, god , nearly all know that! but due to this condition, it is nearly worthless...
I thought the one looked like a Saudi coin.... I spent some time in Malacca myself... went swimming near Port Dickson in the straits....we found the pool to be much more enjoyeable... never found any coins on the beach....just garbage and potential rapists.... However I bought this one back in the states for a dollar....I like the rooster, note how he has large spurs on his legs. They had some very nice old dutch and english headstones in the old fortress at malacca... I took these shots there... its hard to tell since the image is shrunk, but the first headstone, is dutch, and dated 1636... there were dozens like it.
