Free agents Ron Guidry (Yankees), Rich Gedman (Red Sox), Bob Boone (Angels) and Tim Raines (Expos) all re-sign with their former clubs on the first day they are allowed to do so, after being victims of collusionduring the off-season. Doyle Alexander (Braves) will re-sign on May 5th.

On May 1, 1987 — Free agents Ron Guidry (Yankees), Rich Gedman (Red Sox), Bob Boone (Angels) and Tim Raines (Expos) all re-sign with their former clubs on the first day they are allowed to do so, after being victims of collusionduring the off-season. Doyle Alexander (Braves) will re-sign on May 5th.

Source
Baseball Reference May 1