Dragon Scales is a common Enchantment — Aura card from Scourge (SCG), collector number 10. Current market price: $0.15 (foil $1.02), TCGplayer market prices via Scryfall.
Enchant creature Enchanted creature gets +1/+2 and has vigilance. When a creature with mana value 6 or greater enters, you may return this card from your graveyard to the battlefield attached to that creature.