5e SRD:Ring of Regeneration
From D&D Wiki
|This material is published under the OGL|
Ring, very rare (requires attunement)
While wearing this ring, you regain 1d6 hit points every 10 minutes, provided that you have at least 1 hit point. If you lose a body part, the ring causes the missing part to regrow and return to full functionality after 1d6 + 1 days if you have at least 1 hit point the whole time.