Bellore, 28, originally signed on with the Jets as an undrafted free agent out of Central Michigan. Unfortunately, his 2016 season ended with him being placed on injured reserve with an elbow injury.
The Lions cut Bellore loose at the start of the 2017 season only to re-sign him a few days later. He returned to Detroit last year on a one-year contract.
In 2018, Bellore appeared in 14 games for the Lions and caught four passes for 15 yards receiving and no touchdowns.
Mitchell, 31, is a former third-round pick of the Texans back in 2010. He spent four years in Houston before signing a four-year, $19 million contract that included $8 million guaranteed with the Dolphins.
The Dolphins released Mitchell in 2017 and he later agreed to a four-year, $16 million contract with the 49ers. He was set to make base salaries of $2.85 million over the final two years of the agreement when the 49ers declined his option.
In 2018, Mitchell appeared in 14 games for the 49ers and recorded 28 tackles and no sacks.