@Clyde *******
Different immigration offices have different requirements. Expect the following though:
1. Your passport and:
a. a copy of your data ("picture") page
b. a copy of your most recent visa (if you have one)
c. a copy of your most recent stamp
d. a copy of your departure card
2. [May NOT be asked for Bangkok Immigration]A TM30, filed in the immigration office.
3. The forms (each immigration office may have different forms, and want to use their special forms)
4. 2x passport pictures (1x passport picture for Bangkok Immigration)
5. 1,900 THB.