Your search for "Swamp 304" revealed the following:
Swamp (081) - Art Series (Gold-Stamped Signature) (ANEO) from Neon Dynasty Art Series, available at 401 Games Canada. Rarity: Common Finish: Normal Artist: Maiko Aoji
Swamp (010) (PALP) from Asia Pacific Land Program, available at 401 Games Canada. Rarity: Common Finish: Normal Artist: Ron Spears Card Text:T: Add B to your mana pool.
Swamp (033) (Foil) (SLP) from Secret Lair Promo, available at 401 Games Canada. Rarity: Rare Finish: Foil Artist: John Avon
Swamp (015) (PALP) from Asia Pacific Land Program, available at 401 Games Canada. Rarity: Common Finish: Normal Artist: Ron Spears Card Text:T: Add B to your mana pool.
Swamp (015) (PELP) from European Land Program, available at 401 Games Canada. Rarity: Common Finish: Normal Artist: Mike Ploog
Swamp (003) - Arena League Promo 1996 (PARL) from Arena League 1996, available at 401 Games Canada. Rarity: Rare Finish: Normal Artist: Tony Roberts Card Text:T: Add B to your mana pool.
Swamp (048) - The Tokyo Lands - Japanese (SLD) from Secret Lair Drop, available at 401 Games Canada. Rarity: Rare Finish: Normal Artist: Mr. Misang Card Text: The Tokyo Lands
Swamp (033) (SLP) from Secret Lair Promo, available at 401 Games Canada. Rarity: Rare Finish: Normal Artist: John Avon
Swamp (890) - Deceptive Districts (Rainbow Foil) (SLD) from Secret Lair Drop, available at 401 Games Canada. Rarity: Rare Finish: Foil Artist: Alexander Khabbazi
Swamp (005) (PELP) from European Land Program, available at 401 Games Canada. Rarity: Common Finish: Normal Artist: Scott Bailey