The red and gold cloth fragment, which measures 6.5in by 5.5in, was, according to auctioneers, a standard of the future Henry VII, during the pivotal and bloody fight between the houses of Lancaster and York which took place at Bosworth Field in 1485.
Hansons Auctioneers said the piece has strong provenance and is expected to make between £3,000 and £5,000 when it goes under the hammer on Saturday.
Auctioneer Charles Hanson said the fragment was part of a far larger flag carried by Sir Robert Harcourt who was standard bearer to Henry Tudor during the fight.
Henry's forces slew Richard, ending the Wars of the Roses and marking the beginning of the Tudor dynasty which ruled England until 1603.
International interest in King Richard has boomed after human remains uncovered in an old friary beneath a Leicester car park in 2012 were earlier this year confirmed by experts as being those of the late monarch - the last of the Yorkist line, who reigned from 1483 until his death in battle.
He said the flag fragment had been one of three decaying parts originally hung above the tomb of Sir Robert, Knight of The Bath, where he had been laid to rest after his death in 1490.
Sir Robert's tomb in St Michael's Church in Stanton Harcourt, Oxfordshire, is also decorated with the Lancastrian red rose.
Mr Hanson added the material's provenance was "very good" as it had been in the keeping of the same family in Northamptonshire since at least 1847, when it had been mounted in a frame for safe-keeping.
"The fragment had been passed around over the years as an amusing after-dinner thought," he said.
"Our vendors are obviously aware of its social value today since the imagination of what happened at the Battle of Bosworth will keep historians debating for years to come.
"I am just delighted such a fundamental accessory to that 1485 battle has been unearthed only months after finding King Richard III in a Leicester car park.
"As an auctioneer, I thrive on the social relevance such bygone artefacts had on society.
"If only this fragment could talk I am sure it could tell us so much.
"Of course we now know where Richard was laid to rest and I hope this fragment find will be purchased by a museum or private collector who may place it on public display."
He said given the current interest in the Yorkist king internationally, the fragment may fetch "considerably more" than its estimate when it is auctioned in Derbyshire.
Currently, Richard is set to be laid to rest in a tomb being designed for Leicester Cathedral.
A legal challenge by a small group of his distant relatives wants him buried at York.