The Ahsenwheat mod adds a few new crops to the game that can be used for food but more importantly they can be crafted into some rarer items. So now you can just grow them instead of mining for them. The Ashenwheat itself can be made into bread and cookies but all products made from it including the wheat itself can be used as fuel. And if you smelt Ashenbread it can be converted into charcoal.
Thundergrass is a great asset for obtaining gunpowder. The seeds from it can be smelted into Unstable Soot which you can then combine to form gunpowder. So this is a safer alternative to finding gunpowder without involving Creepers.
Ossidroot look a lot like green jack-o-lanterns and can be made into lanterns as well. But if you smelt it into calcified ash, you can turn that into bonemeal.
And Scintillawheat can also be used for bread and cookies but if you smelt the hay bales into Scintillating Ash you can then make Glowstone Dust.