"Lucky charms"[1] are the life-gaining artifacts in Alpha, Crystal Rod, Iron Star, Ivory Cup, Throne of Bone, and Wooden Sphere, and their derivatives in other sets and expansions. The original so-called "lucky charms" were printed in every Core Set through 8th Edition. The art for each card from 5th Edition to 8th (save 7th Edition which was commissioned art by different artists) was illustrated by Donato Giancola.
Angel's Feather from 9th Edition and Ivory Cup from Unlimited.
The original "lucky charm" for white read:
Whenever a player plays a white spell, you may pay
. If you do, you gain 1 life.
Antiquities Lucky Charm
A life-gaining artifact following the theme of the original "lucky charms", Urza's Chalice, was printed in Antiquities.
Darksteel "lucky charms"
Another cycle of life-gaining artifacts, improved versions of the "lucky charms" — Angel's Feather, Demon's Horn, Dragon's Claw, Kraken's Eye, and Wurm's Tooth — were printed in Darksteel, and they have been reprinted in every core set thereafter. Each of these cards was illustrated by Alan Pollack.
The version from Darksteel reads:
Whenever a player plays a white spell, you may gain 1 life.
The newer versions require no activation cost, but are cost more.
Scars of Mirrodin "lucky charm"
Following the theme set in Darksteel, Scars of Mirrodin improved on the original artifact "lucky charm" that was printed in Antiquities. Golem's Heart used the same change as the Darksteel "lucky charms" did, taking out the activation cost, but making it cost more like the Darksteel cycle above.
This card was illustrated by Matt Cavotta.