These are a very fond memory from childhood for me, they are milk sweets and you can't find anything quite like them in the west (they're not chalky, they're far more creamy but without the cream).
If you're in a Thai supermarket or sweet shop, keep an eye out for them, they're worth tasting, even if it's only once.
They're also a good source of calcium. Thai's associate milk with calcium because the yoghurt makers advertise that milk is a good source of calcium. Although we also eat a lot of green leafy vegetables which is also rich in calcium, and so don't really need the extra.
It seems nobody stops to think, where did cow gets the calcium from?!
Look for 'Double Milk' sweets in the pack above.