Silent Forest: Zone 3
Red Star Ring 1: From the very start of the level, after you hit the first boost, jump the gap in front of you, dodge a couple of spike traps and find the Red Star Ring on a platform with a jump pad.
Red Star Ring 2: After a sequence in which you must dodge boulders and a spiky-half-cylinder, you'll be launched onto a couple of raised platforms. Between them, on the bottom level, is an easy-to-miss bell. Chase it across the level and into an underground area for the Red Star Ring.
Red Star Ring 3: From the large, open area in which you found the bell, if you stick to the top level, you'll be propelled into a tunnel and immediately see a section of floor made of purple crystal. Use the stomp to smash through it to a hidden area, where you'll see the Red Star Ring encased in a block of crystal.
Red Star Ring 4: Near the end of the long tunnel with the boulders and the sticky green tiles, you'll see another purple section of floor. Stomp through it and find the fourth Red Star Ring hanging above one of the animal cages.
Red Star Ring 5: Just after the final checkpoint, you'll see a line of rings circling around the far wall. Use Sonic's wall-run to follow them and unveil a hidden jump pad, which will launch you to a new area. Pound through the purple floor here and execute an extremely well-timed chain of wall-jumps to grab the Red Star Ring midway through the chasm.