Bolton have completed the capture of former Crewe striker Max Clayton on a three-year contract.
Felix Magath has been sacked by Fulham, with Kit Symons taking over as caretaker manager.
New Millwall boss Lomas is keen to bring in Southend striker Harris as his first-team coach as he shuffles his backroom team at the club.
Lomas is busy preparing for the start of the new season and he is thought to have made Harris one of his top targets.
Harris is a big fans' favourite at the Den and is the club's record goalscorer with 138 goals to his name.
The 35-year-old, who left Millwall in the summer of 2011 to join Southend, is thought to be keen on moving into coaching and would jump at the chance to work alongside Lomas.
Harris still has a year to run on his contract at Roots Hall, but they are unlikely to stand in his way as he looks to take his first steps into coaching.