These items are added by the Magical Crops mod.
Magic Seeds can be used to grow: Coal , Iron, Redstone, Gold, Lapis Lazuli, Diamonds, Emeralds, Glowstone, Obsidian, Gunpowder, any color of dye, Ender Pearls, Experience, Copper, Netherbrick, and Tin Essences. Growing rarer items (diamonds, gold) will require higher tier magic essence. Harvested Essences can then be crafted into their respective items (i.e. Coal Essence into coal) by placing essence in every single space on the crafting table except for the center space (like making a chest). Or the essence can be made into an Essence block (as you would make a snow block), and the Essence blocks can then be made into Essence bricks (as you would make Nether Brick). However, Essence blocks and Essence bricks are only for aesthetic uses.
Growth & Growing Conditions
All of these seeds mostly function like vanilla minecraft seeds. The seeds must be planted on farmland, they require a specific light level, and they will grow faster if the farmland is hydrated (water is nearby the farmland). Bonemeal can be only be used on Dye Seeds and Obsidian Seeds. Bonemeal doesn't instantly grow crops, but it will bring the crop through a couple stages of growth.
When fully grown these magic seeds will drop 0-3 seeds, 1 Essence of whichever seed you planted, 0-3 Weak Magic Essence, and 0-1 Nature Essence. If they are harvested early all they will drop is seeds.
Low Tier Seeds
Dye Seeds (Works with all dye)
Medium Tier Seeds
Lapis Lazuli Seeds
High Tier Seeds