These photos were taken in natural sunlight. They are the Baht and its fractional silver pieces from the popular King Chulalongkorn. These are the brightest examples without toning I could put together.
There are also copper pieces that can still be found looking not too dark, with a slightly different, even better portrait of the King. I believe there was no 1/2 Baht for this time.
The examples of these coins we have that were given higher grades look duller.
The most common Baht is "no date" (1876-1900) just like the 1/4 and 1/8 Baht coins shown here. The 1903 (RS 122) Baht included here is a little more scarce, but not that much. The RS means "Rattanakosin". The Rattanakosin Era began 1781, about the same time the USA was getting started. So, 122 is 1903. If you look at the worn and beaten Baht coins available on Ebay they can often be found advertised as "1876-1900" or "ND" when they are actually dated, RS 120 through, maybe, 127.
There is a very worn coin ending on Ebay now, the reverse picture is below. It is at just $16. It is listed as 1876-1900. But the date appears at the very bottom on the reverse, here.
If there is no date, there is no 3-character thing at the very bottom. This one, like all of them, is "1 2 __". I am pretty sure, after a careful review of Thai numbers, that it is 1 2 0.
That makes this a pretty scarce 1901 Baht. In AU55 or better without problems it would sell for $700 to $1000. This coin likely has more problems than just heavy wear. Maybe it is F. It doesn't matter much. I will try to pick it up, they make great gifts for Thai kids. This is recognizable as the portrait of the most popular and famous king in Thailand. People are coming to light smell sticks and leave whiskey in front of his statue in front of the Parliament building every night.