Sony just announced which games will be free for PS+ members for June 2019.
First is Borderlands: The Handsome Collection which includes both Borderlands 2 and Borderlands: The Pre-Sequel. This will prep players for the upcoming Borderlands 3. Not only does The Handsome Collection include all DLC for both titles, enhanced local multiplayer and remastered visuals, but if you played either title on PS3 you can carry over your save data and can pick up where you left off in the PS4 version.
Then, Sonic Mania will also be free for Playstation Plus members.