Toad House
Toad Houses are Mushroom-shaped buildings that first appeared in Super Mario Bros. 3, where they were located across every world map except for Dark Land. They have since made appearances in more recent games. Toad Houses always hold either a useful surprise or reward for the player.
History
Super Mario series
Super Mario Bros. 3
Upon entering a Toad House, Toad will appear and present the player with three Treasure Chests, each one containing a different item. Toad Houses in earlier worlds tend to hold more basic power-ups such as Super Mushrooms and Super Leaves, while the ones in later worlds may hold Tanooki Suits and Hammer Suits. The player may only open one chest, after which, the Toad House will disappear.
In World 1-3, if the player presses and holds 
on the white block, Mario or Luigi will then be "behind" the level's objects (bushes, blocks, enemies, etc.). If the player keeps running right and behind the black background at the end of the level, they will enter a secret Toad House, where they will acquire a Warp Whistle.
White Toad House
If a player collects a certain amount of coins in a world's particular level, a White Toad House will appear (in remakes of the game, these Toad Houses are blue). Within these special Toad Houses lie a single chest. A P-Wing can be found in the chest in odd-numbered worlds, while an Anchor will appear in even-numbered worlds.
New Super Mario Bros.
Toad Houses reappear in New Super Mario Bros. on the world map, often requiring Star Coins to open up (or completing a bonus, lettered level). Toad Houses (except the Mini House) disappear after one use. However, if the brothers can complete all eighty levels in the game, all Toad's Houses will reappear and become permanent (marked by a blue circle on the world map), providing up to 99 lives and infinite items to help find all the Star Coins. Manned by Toadsworth, they supply all the helpful items in the game in four different varieties:
Power-Up Toad House
Power-Up Toad Houses are capped by a red mushroom on the world map. A giant Roulette Block alternates between a Mushroom, Fire Flower, Blue Shell and a Mini Mushroom. Whatever is displayed when Mario or Luigi bumps it from below is what will be stored as the backup item. If a brother has a backup item already and the item chosen has less or equal value to the original backup item, 1000 points will be awarded instead.
1-Up Toad House
1-Up Toad Houses are capped by a green mushroom. Six ? Blocks are spread out. Three contain a 1-Up Mushroom card. One contains a 1-Up Mushroom X3 card, which is equal to 3 1-Ups. One contains a X2 card. One contains a Bowser card. The X2 card doubles all cards already revealed, and the Bowser card ends the minigame (though Mario keeps any 1-Ups revealed). Up to twelve 1-Ups can be won.
Mega Mushroom Toad House
Mega Mushroom Toad Houses are Mushroom Houses that look like Mega Mushrooms in New Super Mario Bros.. When Mario or Luigi enter this house, Toadsworth will create a Giant ? Block. When hit, a Mega Mushroom will appear. The Mega Mushroom gained from the Mega Mushroom House will override any item in the item slot. Like other houses featured in New Super Mario Bros., Mario will usually have to pay five Star Coins to pass the signpost leading to the Mega Mushroom House. These Toad houses are featured in every world of New Super Mario Bros..
They do not reappear in New Super Mario Bros. Wii because of the fact that there is no Mega Mushroom in this game.
Blue Toad House
A single Blue Toad House is found at the beginning of World 1 after beating Bowser and saving Princess Peach. Inside it, there are blocks with different designs on them. These are the different backgrounds the player can select for their Nintendo DS' touch screens, and they cost twenty Star Coins each. After Mario or Luigi collects all the Star Coins in the game, a fifth background can be chosen.
Bonus Toad Houses via Flag Fireworks
By ending the level with the last two numbers of the time limit being the same (except 00), three things are triggered: The Super Mario Bros. "Level Clear" theme is played instead of the normal one, fireworks go off (1 for ending in 11, 2 for ending in 22, and so on, awarding 4,000 points per explosion for a maximum of 36,000), and a bonus Toad House appears at the starting point where Mario first enters the world. Time limits ending in 11, 22, or 33 yield a Power-Up Toad House, 44, 55, and 66 yield a 1-Up Toad House, and 77, 88, and 99 yield a Mega Mushroom Toad House. None of these houses are permanent, even after completing all of the levels in the game.
New Super Mario Bros. Wii
Unlike New Super Mario Bros., this game does not require Mario to collect Star Coins to open Toad Houses. Instead, the player will automatically unlock it when a certain level is completed. Also, a Toad House will appear at the start of the World if Fireworks are triggered, like the prequel. In single-player, this is accomplished by rescuing a Toad. In multiplayer, all players must reach the flagpole when the last two digits of the remaining time are the same. In both modes, the last digit of the remaining time tells how much fireworks are set off and each one adds 4,000 points to the player's game score. After using a Toad House, the players will get a tip, reminding them to use them on a tough course. Or if the players used a 1-Up House, they will get a message about visiting Princess Peach's Castle to watch Hint Movies. There are three colors of Toad Houses. Red, Green, and Yellow. If Mario gets a red Toad house, he will play Power-Up Panels. If he gets a green Toad House, he will play the game 1-Up Blast. If he gets a yellow one, he will get a Starman.
Power-Up Toad House
In Power-Up Toad Houses, Power-Up Panels is played by matching two of the same items. If two Bowser or Bowser Jr. tiles pop up, the game will end and Mario keeps his items he either earned from the game.
1-Up Toad House
In 1-Up Toad Houses, 1-Up Blast is played by hopping into a cannon and players hit 
to shoot out and pop balloons.
Star Toad House
Star Toad Houses contain one Star in a chest, and they are much rarer than the other Toad Houses. These houses have white roofs with multiple stars around the house.
Bonus Toad Houses via Flag Fireworks
Like in New Super Mario Bros., Toad Houses can appear at the starting points of worlds by using the same strategy. In multi-player mode, the strategy is exactly the same, but since there are no Mega Mushroom Toad Houses, Star Toad Houses appear when the time limit's last two digits show 77, 88, or 99. In single player mode, the strategy is slightly different. Instead of finishing the stage with the last two digits of the time limit being the same, if Mario or Luigi saves the Toad in the level and takes him to the end, only the last digit counts (e.g. 1, 2, and 3 make a 1-Up Mushroom Toad House appear instead of 11, 22, and 33). Once again, these Toad Houses aren't permanent unlike the others.
The Adventures of Super Mario Bros. 3
In The Adventures of Super Mario Bros. 3, Toad Houses were shown to be the actual residences of the Mushroom People living in the Mushroom Kingdom. Toad's house in particular was a frequently used location during the course of the series. In addition to the houses, most commercial buildings were shaped like Mushrooms, such as the Mushroom Land Central Library and the Mushroom Kingdom Orphanage.
Paper Mario series
Paper Mario
In Paper Mario, Toad Houses became a place where Mario and his partners could restore their HP, FP, and SP. They appeared in almost every town, and they were each run by a Toad. In the later Paper Mario games, the Toad Houses were replaced by Inns.
Trivia
- Beta screenshots of Super Mario Bros. 3 showed that Toad wouldn't be the only one hosting Toad Houses - a Koopa and a Hammer Bro. would also run the Toad Houses.
- Beta screenshots of Super Mario World showed Toad Houses would appear in this game.
- Toad House's music in New Super Mario Bros. Wii is a remix of Toy Time Galaxy from Super Mario Galaxy.
- In Paper Mario, the Toad House in Goomba Village has the slogan "Refresh your body and mind", while the others are "Refresh your body and soul".
- In Mario Party 3, the buildings on the party board are similar to Toad Houses.
