There are five colours of mana, with starting decks tending to choose one or two to play (generally, the more colours of mana in a deck, the harder it is to play effectively)
There are so many green cards that help make extra mana, find lands from your deck to put them into play, or turn your creatures into lands, or do something else that somehow produces mana, that it's simply impossible to list them all
That guaranteed special land from the Stellar Sight bonus sheet, a chance at special guests and borderless shock lands bring a fan-favorite set to a sleeve near you
In the recent discussion post regarding the MTGA economy, Wotc gave a clear and authoritative position against dusting being introduced into the game: We never wanted players to feel pressured to dismantle their collection to build the deck they want, only later to be disappointed when they realize they need to reacquire cards they destroyed
Its best to save these points for when your deck is close to complete
