The 49ers have fielded calls from at least three teams in the past week inquiring whether Garcon is available, and San Francisco has listened to what others are offering as talks are expected to continue following Sunday's game against the Arizona Cardinals, sources told ESPN.
"Teams call about a lot of people," Shanahan said after the game. "I think every team around the league is doing a ton, so I know there was a report on Pierre. That is true. He's one of the guys that people have asked about and we have talked about, but nothing is going down right now. We'll see how these next two days play out with Pierre and a lot of people."
Garcon, 32, is the type of veteran receiver whom some teams covet because of his talent and leadership. He also is scheduled to make $6.6 million in base salary this season and $5.6 million next season, making him even more attractive to teams.
"We'd love Pierre back, he's just trying to get his knee healthy, which he's very close to," Shanahan said. "We expect him to be good for Thursday night. We have looked into everything. Teams have talked about him, and it is a possibility, but nothing for sure right now."
Shanahan also said he has kept Garcon informed of trade discussions.
San Francisco is not expected to reach the postseason and could be willing to part ways with Garcon in the hopes of receiving a draft pick in return. Garcon has 21 receptions for 230 yards in seven games this season, his second with the Niners.
ESPN's Nick Wagoner contributed to this report.