The 32-year-old has been linked with transfers to Scunthorpe, Grimsby Town, Rotherham United and Bradford City already this summer but is now thought to be on the verge of joining the Robins.
Boulding scored 25 goals for the Stags last season as they were relegated out of the Football League, but now looks set for a move to Whaddon Road according to the Robins boss Keith Downing.
"He's got plenty of interest from elsewhere but he's keen to play at the highest level he can, so we have a chance and it's up to us to try and secure him," he said.
"I've spoken to Michael and we're a bit further on down the line with it, hopefully we can finalise the talks."