The background confers two skills (usually two skills and two languages, tools, instruments, etc.) and a story / global interaction type characteristic, not something like damage resistance.
The Infernal Constitution feat (Xanathar page 75) gives you resistance against poison damage (and an advantage over poison saves). However, that forces you to be a tieffelin who doesn't get a wisdom bonus.
All dwarfs (PHB pages 18-20) gain resistance to poison and hill dwarfs receive a bonus to their wisdom.
Aasimar (Volo & # 39; s pages 104-105) get resistance to necrotic damage and protective assimars get a bonus to wisdom.
Dragonborn (PHB pages 32-33) obtains resistance to a type of damage which, for greens, is poison. They don't get bonuses for their wisdom, however.
Yuan-Ti (Volo & # 39; s page 120) get immunity from poison damage, but no bonus to their wisdom and as a monstrous adventurer you should mostly talk with your DM about the availability and the place of the breed in this world.
Partly mentioned because he is not available to initiate magic as poison protection is a 2nd level spell. It is however a spell on the list of clerics that confers resistance to poison damage and an advantage over backups against the poisoned condition, in addition to neutralizing existing poisons.