A list of all the ways you can restore PP, for casting PSI, in EarthBound.

Sleep
The easiest way to restore PP (and HP) is to sleep. In Onett, you can talk to your Mom to sleep for free, or get a room at the Onett Hotel. As you progress through the game, there are hotels in other towns, but they get more expensive the farther you are from home. There are other free places to sleep, such as the Miners' Shack in Dusty Dunes Desert, and the hotel in Saturn Valley.
Lucky Sandwiches
Early in the game, the only item you can get that restores PP is the Lucky Sandwich, which only has a 12% chance of restoring PP, and usually it only restores 5 PP. They restore HP 88% of the time, so they're still useful. Bakeries and some drug stores sell Lucky Sandwiches, and you sometimes find them in gift boxes.
Magic Butterflies
As you walk around, sometimes you will see a sparkling Magic Butterfly. Catch it and everyone in the party (except Jeff) will recover about 20 PP.
PSI Magnet Spells
PSI Magnet α absorbs between 2 and 8 PP from a single enemy and costs 0 PP to cast. Paula learns it at level 15, and Poo learns it at level 21. Similarly, there is PSI Magnet Ω, which works the same way but drains PP from all enemies, rather than from a single target. Paula learns PSI Magnet Ω at level 24, and Poo learns it at level 27. Unfortunately, Ness can't learn this spell, so he will need to rely on items to recover his PP.
You can use the PSI Magnet spells to not only recover PP for free, but also to reduce the PP of magic-using enemies, reducing the number of spells that they can cast. This spell doesn't drain PP from enemies that don't use magic, however.
Magic Truffles
There are only six Magic Truffles in the game, most of which are in the Deep Darkness. One can be obtained from an unnamed NPC in the Threed Hospital. Magic Truffles restore 80 PP and go well with the Ketchup Packet. For full details on how to get the six Magic Truffles in EarthBound, see Where to Get Magic Truffles.
Items You Can Buy to Restore PP
Aside from the Lucky Sandwiches mentioned above, you eventually find some shops that sell items that recover PP:
- Brain Food Lunch: The restaurant in Dalaam sells Brain Food Lunch for $800. It restores 300 HP and 50 PP to everyone but Poo, who recovers all PP when he eats Brain Food Lunch. If you have a Salt Packet or Jar of Delisauce in a character's inventory with the Brain Food Lunch, whoever eats it will get full HP and PP recovery.
- Magic Tart: After Poo joins you, the Magic Cake lady in Summers starts selling Magic Tarts for $480 at her cart. They restore 20 PP and go well with the Sugar Packet.
- Magic Pudding: You only get to visit Magicant once, so you might want to stock up on Magic Puddings, which you can buy at the Magicant Shop for $680. They restore 40 PP and go well with the Sugar Packet.
Items for Poo to Recover PP
There are two PP recovery items that only work well for Poo: the Bottle of Water and the Bottle of DXWater. Most characters only get 1 PP from these, but Poo gets 10 PP from the Bottle of Water, and 40 PP from the Bottle of DXWater. You can buy these at the following locations:
Bottle of Water Sellers ($4)
- Toto Shop
- Scaraba Food Store
- Dalaam Restaurant
Bottle of DXWater Sellers ($198)
- Scaraba Water Shop
- Southern Shop in Scaraba
- Deep Darkness Shop
- Cave Boy in Winters Lab
- Lost Underworld Shop