Upvote:2
You don't list your nationality, but if you are from one of the 55 countries that qualify for visa exempt entry, you will get a 30 day entry stamp upon arrival and then again when you return from Laos.
The issue will be the airline you fly from home to Thailand with as they are supposed to check that you are leaving Thailand before 30 days. Normally an air ticket is required for this. As you didn't really specify what your ticket to Laos was, the trip to Laos may or may not satisfy the airline staff.