More than 30 events are being held to mark the inaugural Suffolk Day.
It is to recognise the county known for its chocolate-box villages, Ipswich Town Football Club, 50 miles (80km) of coastline and horseracing at Newmarket.
Suffolk Day is based on a successful model in Yorkshire and is planned to be held annually.
As part of the day's events, bells at 14 towers are ringing out, including at Fressingfield, East Bergholt, Sproughton, Elmsett and Debenham.
Students and staff at Otley College have dressed up as Sheeran, who grew up near Framlingham, showing their love for the county's famous "son".
Children were dressed as the singer, and they even found a ginger dog to join in the celebrations.
More news about Suffolk Day
Elsewhere, there are events including dancing, theatre productions, food tastings, live music and a celebration of the county's literary riches.
Candles will be lit at Felixstowe beach in memory of loved ones at the end of the day.
The idea for Suffolk Day was put forward by BBC Radio Suffolk and is being backed by Suffolk County Council and the East Anglian Daily Times.
A Suffolk County Council spokesman said: "We have so many things to be proud of in Suffolk.
"It's not always in our nature to shout about things, we tend to be quite a modest bunch, but this is a great opportunity for communities to come together in celebration of our great county."
A "modest" county's first ever day of celebration has included street parties, food tasting and students dressing up as singer Ed Sheeran.