The 32-year-old left Home Park at the end of the last campaign following a host of injuries, but he has returned to the club for pre-season training.
Sheridan told the club's official website: "He's been biting at the bit. He's trying to impress me. He hasn't played for a long time. He came on and worked hard, and it's always nice to get a goal.
"It's his first game. I don't want to get carried away just because he scored. I thought he did okay when he came on. It was encouraging. He's had a bad injury but he's worked his socks off in pre-season.
"I know what he can do. He knows how to play the game. I've got some good strikers in and around the team and I've got good options to play people up there, and I'm still looking at attack-minded players."
Feeney scored in Plymouth's 1-0 win over Tiverton in a pre-season fixture on Saturday.