Here is an entry from WikiTravel....take it for what it's worth:
So the station is technically within the town of Plymouth, but not near downtown Plymouth and not near the Mayflower or the Plimouth Plantation or Plymouth Rock. The section where the station sits is Cordage Park. Some current MBTA maps now refer to the station as Cordage/Plymouth.Take the Plymouth/Kingston line from Boston's South Station on the MBTA Commuter Rail, until terminal at Plymouth station. Trains alternate on this line, ending either at Kingston or Plymouth. The Plymouth terminal is at Cordage Park, about a mile away from the main tourist area. From there you can take a GATRA bus or call a taxi.
The Walmart (now empty building) that the station is behind closed in 2005 when a Walmart Super Center opened out by Route 3 as part of a big box center.