Yes. You can get one 30 day visa extension on every visa exempt entry.
You can also get two visa exempts in a calendar year by land (if you are from a visa exempt country).
A visa exempt country can be found on this page here.
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%20on%20Arrival/VOA.pdf
When you go to the local immigration office, just give them 1,900THB, and you'll get your 30 day extension.