Puff-shroom

The Puff-shroom is the first mushroom the player gets, and although it has an incredibly short range, it's free since sun is much harder to come by at night. They are nearly as effective as Peashooters, but only have a three column shooting range. Of course, as a mushroom, they are only awake at night, and their short range makes the expense of waking them up with a Coffee Bean a waste of sun. They also have a fast recharge, so the player can plant two of them in 15 seconds for no cost. They are also too small to be shot by Peashooter Zombies and Gatling Pea Zombies.

Suburban Almanac Entry
Puff-shroom 

Puff-shrooms are cheap, but can only fire a short distance.

Damage: normal

Range: short

Sleeps during the day

"I only recently became aware of the existence of zombies," says Puff-shroom. "Like many fungi, I'd just assumed they were fairy tales or movie monsters. This whole experience has been a huge eye-opener for me."

Cost: 0

Recharge: fast

Strategies
Because of their short range, they can only handle basic zombies, unless used in multiple columns, so more effective plants should be added to the player's defenses mid-level. Another strategy is to fill the stage from column four over and replace the back ones when the player can. These plants can also be used to stun Gargantuars and Giga-gargantuars in Survival: Endless, due to the free cost allowing players to sacrifice them to force the Gargantuars to stop and smash them. Puff-shrooms work well in conjunction with defensive plants as the Puff-shroom has plenty of time to fire at the zombies before getting eaten. These may also be helpful in ZomBotany and ZomBotany 2, as they are too short for the zombies to hit them with peas, making them a good choice for both attacking and stopping Squash Zombies. However, they need Coffee Beans to be waken up, removing one of its biggest advantages - being free.

One of the most well-balanced defenses for the night levels uses two columns of Puff-shrooms (in columns three and four from the right, although a third can be added in column two or five) behind which one or two columns of Fume-shrooms are planted. Behind these are planted two rows of Scaredy-shrooms for long range attacking, with a row of Sun-shrooms to produce sun. They can also be used to stop the Pole Vaulting Zombies that come in the early game in the night levels when replaying Adventure Mode, but unless the player has three columns of them, they still have a chance to get by his or her Puff-shrooms. While Puff-shrooms lacks in range, he makes up for in both cost of sun and numbers.

Note: Puff-shrooms can have problems with even regular zombies, and may get eaten due to several zombies attacking in rapid succession.

Photosensitive
In order to gain the Nintendo DS achievement Photosensitive, Puff-shrooms are extremely important. The rest of the selected plants are not important, since the player cannot plant them. Wall-nuts, Potato Mines and Scaredy-shrooms can be used, but the player can only plant either one Wall-nut or two of the others. The easiest level to achieve this is on Level 2-1, as the only zombies that appear are the regular zombie and the Newspaper Zombie. Simply plant three to four columns of Puff-shrooms at the back of the lawn (the player should not plant Sunflowers, as they may be tempted to collect sun, therefore failing this achievement). Due to their free sun cost, the player should not worry if the zombies eat his or her Puff-shrooms and instead continue to plant and replace his or her Puff-shrooms, and he or she should easily achieve Photosensitive.

Trivia

 * The Puff-shroom, the Sea-shroom and their Imitater forms are the only plants in the game that cost no sun.
 * However, they are not the only plants that cost 0 sun. In Plants vs. Zombies 2: It's About Time, the Iceberg Lettuce and Grave Buster (along with their Imitater forms) cost 0 sun.
 * A Puff-shroom is too small for a Pumpkin, but when it shoots a spore, the spore passes through the Pumpkin's shell and still damages the zombies.
 * The Puff-shroom is the smallest plant in the game, apart from the Potato Mine when it is unarmed.
 * The Puff-shroom, the Sun-shroom, the Spikeweed and the Spikerock are the only plants which, when planted, may not be in the center of a square on the lawn. They may get planted slightly to the left, right or up.
 * The Puff-shroom, the Fume-shroom, the Gloom-shroom and the Sea-shroom are the only short-ranged shooters.
 * The Puff-shroom and the Sea-shroom are the only shooters with a three column range.
 * The Puff-shroom is one of the two cheapest plants in Versus Mode, requiring only 25 sun for the cost of the Coffee Bean with the other being the Potato Mine.
 * Even if the Puff-shroom is at the edge of the red line in Versus Mode, it cannot shoot the Target Zombies, as the distance is just slightly over three squares long. The only time it can shoot the Target Zombie, however, is if its spore goes past a dead zombie about to fall down.
 * On the iPad version of Plants vs. Zombies, the spore range increases to four squares.
 * On the Nintendo DS and online versions of Plants vs. Zombies, if a Puff-shroom shoots an already dead zombie (after falling), the spore will pass through the entire lawn.
 * The player will receive a warning if he or she does not choose Puff-shrooms on the first night level. The warning will say "This Level will be extremely difficult without Puff-shrooms. Are you sure you wish to continue without them?"
 * The Puff-shroom, the Twin Sunflower, the Sunflower, the Sun-shroom and the Sea-shroom are the only plants not allowed to be used in Last Stand and the iOS puzzle mode variation.
 * Puff-shroom, Peashooter, Wall-nut and Jalapeno are the only plants referenced to in another plant's Suburban Almanac entry.
 * In this case, the Puff-shroom is mentioned in Fume-shroom's Almanac Entry.