Defenders Anthony O’Connor and Carl McHugh both scored from Bobby Reid set-piece deliveries and held on for all three points despite Vadaine Oliver’s stunning acrobatic effort.
The result sees the Pilgrims move above Newport into the final play-off spot with four games to play.
Sheridan said: “It’s a massive three points for us. At the end of the day the most important thing was to get the win and get back in the play-off places and the players have done that.”
“We can obviously play a lot better but all that matters at the moment is getting the three points.
“It’s a great result as far as we are concerned because we have got the three points and obviously results around us has enabled us to get back in the play-off position.
“They had to try and come and get something because of the position they are in so they are always difficult games, because we want the points to get in the off places.
“We got off to a great start which helped us and I thought after that we could have controlled the game a little bit better in the first half.
“We had them watched last week and they should have beaten Shrewsbury, who are top of the table.
“I was never expecting an easy game especially as we know the importance of getting back into the top seven.
“We’ve got four league games to go and another big game on Tuesday, we have just got to get the result we want.
“We now look ahead to Wimbledon and the same result will do me just fine.”
Mansfield manager Adam Murray said: “I have been wondering how we have been coming away from games without getting results for a few weeks now.
“At the minute we are missing certain ingredients. People are given certain jobs to do and that’s been the story of the season because individual errors have cost us.
“Two set pieces have undone us again, there’s no hiding place from it.
“We know we have got good enough players to compete but it’s putting the ball into the back of the net that is our hindrance at the moment.
“We are not making the most of the chances we are creating. I think Plymouth had three shots on target and they end up with two goals and that’s the difference, that’s why they are in the play-offs are we are not. If we had that ruthlessness in both boxes we’d be up there.
“We had enough of the game to have won it and should have.
“We go into four games in three weeks and we have got to give it our maximum and get something, starting with a massive game at home to Tranmere on Tuesday.”