Amendola and Patricia spent a half-decade together in New England before both left for more money elsewhere in 2018.
Deals can not become official until the start of the new league year, at 4 p.m. ET on Wednesday.
In 15 games last season, the 33-year-old caught 59 passes for 575 yards and one touchdown.
Flowers is expected to sign a five-year contract reportedly worth in excess of $16 million per year, according to ESPN's Adam Schefter.
The Detroit Lions have signed wide receiver Danny Amendola following his release by the Miami Dolphins.
Ian Rapoport of NFL.com reports the deal is for one year and includes a $4.5 million guaranteed salary base which can become as high as $5.75 million with incentives.
The former fourth-round pick might not be a Von Miller-type edge rusher, but is a prototypical moveable chess piece along the front-line that Patricia covets from his defensive players.
When it comes to the Detroit Lions, trying to determine who might be their targets in free agency comes with one prerequisite: Have they played for the New England Patriots before?