Here is tonight's find. It was in the same field as the other two in the OP.
It is a silver penny of James I dating from around 1620. James was the son of Mary Queen of Scots and Lord Darnley. The room in Edinburgh Castle where he was born is visited by thousands of tourists every year. He succeeded to the Scottish throne as James VI of Scotland in 1567 aged 13 months. His mother - a Roman Catholic - was forced to abdicate and flee into England where she hoped to find refuge with her cousin Queen Elizabeth I. Instead she spent 20 years in custody before being beheaded at Fotheringhay Castle. James, who had been raised to believe the propoganda about his absent mother did nothing to assist her.
When Elizabeth died childless in 1603 James, the great-grandson of Margaret Tudor, inherited the English throne resulting in the Union of Crowns. He was crowned James I of England.
The coin has an English Rose on one side and a Scottish thistle on the other.
The inscriptions read ...
I D G ROSA SINE SPINA = 'James by the Grace of God a rose without a thorn'
TUETUR UNITA DEUS = 'May God guard these United Kingdoms'
I haven't posted a pic of the other side as it is in very poor condition.