22 cards where the text includes “saproling” and it’s legal in Historic

Blightreaper Thallid // Blightsower Thallid (March of the Machine #92)
Blightreaper Thallid // Blightsower Thallid (March of the Machine #92)
Deathbloom Thallid (Core Set 2021 #94)
Fungal Infection (Dominaria #94)
Fungal Plots (Commander Masters #291)
Fungal Rebirth (Ravnica: Clue Edition #163)
Nemata, Primeval Warden (Dominaria United #209)
Overgrown Armasaur (Rivals of Ixalan #141)
Saproling Migration (Dominaria #178)
Slimefoot and Squee (March of the Machine Commander #447)
Slimefoot, the Stowaway (Commander Masters #356)
Sporecrown Thallid (Dominaria #181)
Sporemound (Commander Legends #437)
Spore Swarm (Dominaria #180)
Sporeweb Weaver (Core Set 2021 #208)
Tendershoot Dryad (Rivals of Ixalan #147)
Thallid Omnivore (Dominaria #106)
The Mycotyrant (The Lost Caverns of Ixalan #235)
The Weatherseed Treaty (Dominaria United #188)
Undercellar Myconid (Commander Legends: Battle for Baldur's Gate #259)
Verdant Embrace (Forgotten Realms Commander #173)
Verdant Force (Dominaria #187)
Yavimaya Sapherd (Dominaria #189)

Though this query has ended, its relics still slumber in New Argive.