One other thought about why Sam was at the Green Dragon, even though it was not quite his local pub:
In "The Scouring of the Shire" we read that Farmer Cotton's house was "down South Lane" from the Green Dragon, seemingly nearby. Perhaps Sam wanted to spend time at the Cotton family's local pub for some reason or other. Of course, we won't find out his reason for a long, long time. But it's nice the way this insignificant detail from the opening chapters ties in so well with the ending details not written by Tolkien until years later. At least, I assume they were written years later.
In "The Scouring of the Shire" we read that Farmer Cotton's house was "down South Lane" from the Green Dragon, seemingly nearby. Perhaps Sam wanted to spend time at the Cotton family's local pub for some reason or other. Of course, we won't find out his reason for a long, long time. But it's nice the way this insignificant detail from the opening chapters ties in so well with the ending details not written by Tolkien until years later. At least, I assume they were written years later.