History of CR 202.1b

Every distinct wording since 2010, newest first.

July 12, 2019 · Core Set 2020
Some objects have no mana cost. This normally includes all land cards, any other cards that have no mana symbols where their mana cost would appear, tokens (unless the effect that creates them specifies otherwise), and nontraditional Magic cards. Having no mana cost represents an unpayable cost (see rule 118.6). Note that lands are played without paying any costs (see rule 305, “Lands”).
May 3, 2019 · War of the Spark
Some objects have no mana cost. This normally includes all land cards, any other cards that have no mana symbols where their mana cost would appear, tokens (unless the effect that creates them specifies otherwise), and nontraditional Magic cards. Having no mana cost represents an unpayable cost (see rule 117.6). Note that lands are played without paying any costs (see rule 305, “Lands”).
January 25, 2019 · Ravnica Allegiance
Some objects have no mana cost. This normally includes all land cards, any other cards that have no mana symbols where their mana cost would appear, tokens (unless the effect that creates them specifies otherwise), and nontraditional Magic cards. Having no mana cost represents an unpayable cost (see rule 117.6). Note that lands are played without paying any costs (see rule 305, "Lands").
May 1, 2014 · Journey into Nyx
Some objects have no mana cost. This normally includes all land cards, any other cards that have no mana symbols where their mana cost would appear, tokens (unless the effect that creates them specifies otherwise), and nontraditional Magic cards. Having no mana cost represents an unpayable cost (see rule 117.6). Note that lands are played without paying any costs (see rule 305, “Lands”).
September 30, 2011 · Innistrad
Some objects have no mana cost. This normally includes all land cards, any other cards that have no mana symbols where their mana cost would appear, tokens (unless the effect that creates them specifies otherwise), and nontraditional _Magic_ cards. Having no mana cost represents an unpayable cost (see rule 117.6). Note that lands are played without paying any costs (see rule 305, "Lands").
June 17, 2011 · Commander 2011
Some objects have no mana cost. This normally includes all land cards, any other cards that
April 1, 2011 · Duel Decks: Knights vs. Dragons
Some objects have no mana cost. This normally includes all land cards, any other cards that have no mana symbols where their mana cost would appear, tokens (unless the effect that creates them specifies otherwise), and nontraditional _Magic_ cards. Having no mana cost represents an unpayable cost (see rule 117.6). Note that lands are played without paying any costs (see rule 305, "Lands").
February 4, 2011 · Mirrodin Besieged
Some objects have no mana cost. This normally includes all land cards, any other cards that have no mana symbols where their mana cost would appear, tokens (unless the effect that creates them specifies otherwise), and nontraditional Magic cards. Having no mana cost represents an unpayable cost (see rule 117.6). Note that lands are played without paying any costs (see rule 305, “Lands”).
October 1, 2010 · Scars of Mirrodin
Some objects have no mana cost. This normally includes all land cards, any other cards that
July 16, 2010 · Magic 2011
Some objects have no mana cost. This normally includes all land cards, any other cards that have no mana symbols where their mana cost would appear, tokens (unless the effect that creates them specifies otherwise), and nontraditional _Magic_ cards. Having no mana cost represents an unpayable cost (see rule 117.6). Note that lands are played without paying any costs (see rule 305, "Lands").
February 1, 2010 · Worldwake
Some objects have no mana cost. This normally includes all land cards, any other cards that have no mana symbols where their mana cost would appear, tokens (unless the effect that creates them specifies otherwise), and nontraditional _Magic_ cards. Having no mana cost represents an unpayable cost (see rule 116.6). Note that lands are played without paying any costs (see rule 305, "Lands").