Evidence of prehistoric activity had already been uncovered in the same area of the site near Norton Bridge and archaeologists believed the butter churn could be from the same period.
But radiocarbon tests have revealed the lid of the butter churn dates from the early medieval period when the area was part of the Mercian kingdom.
The tests have put a fragment of wood found with the lid as dating between AD715-890, so the lid is from the same period as the Staffordshire Hoard.
Dr Emma Tetlow is senior archaeologist at the site where Network Rail is building a new flyover and 11 bridges to remove the last major bottleneck on the West Coast main line, as part of the £250m Stafford Area Improvements Programme.
Hundreds of thousands of tonnes of earth have been moved at the site to date, but checks are undertaken by Dr Tetlow during ground works. She said she was surprised but delighted by the news as there was so little evidence of this period archaeologically.
“During this period this part of Staffordshire was part of the Mercian heartland and was populated by a pagan tribe called the Pencersaete.
“Existing knowledge of this period for the north and east of the Midlands and the UK in general is very scarce, so this find is fantastic and of regional significance.”
“This was a period of dynamic climate change culminating in the Medieval Warm Period. The weather patterns were similar to those we are experiencing today.
“It was increasingly unsettled and stormy with flooding and an increase in temperature.”
The finds – along with further evidence of worked wooden stakes and wood chips – were made in a section of waterlogged peat close to Meece Road.
A number of Victorian stoneware bottles bearing the names of breweries from Bristol to Manchester have also been unearthed.
Local residents will have the chance to view some of the objects and discuss them with Dr Tetlow and other colleagues working on the site at an information day in June. She is also preparing a paper on the finds for the Stafford and Mid-Staffs Archaeological Society.
Staffordshire Alliance manager Matt Clark said: “Despite a challenging workload and at times some challenging weather we’ve worked hard with Emma to safeguard archaeology at the site and it’s been fascinating so see what she’s uncovered.
“We’re looking forward to sharing and discussing some of these finds with the community.”
The work is being delivered by the Staffordshire Alliance – a partnership of Atkins, Laing O’Rourke, Network Rail and VolkerRail.
Local residents wanting further information about the work should contact Network Rail’s national helpline on 03457 114 141; email: CRNW[at]networkrail.co.uk; or visit www.networkrail.co.uk/StaffordImprovements