From the Super Mario Wiki
Inga is the innkeeper from Flopside in Super Paper Mario. According to Tippi and Tiptron's tattle, she is cunning and always has a sly smile on her face. She also wants to run a string of hotels and become the number one hotelier. Her inn looks like a haunted mansion, only it has a spinning electric fan on the ceiling. She will let the heroes stay for ten, twenty, or forty coins a night. This reason is because she also sells breakfast, and the heroes must purchase either the Mushroom package, the Flower package, or the Star package to stay. Depending on which package the heroes purchase (each package has different prices), they will get an item that restores a certain amount of HP. In the morning, Inga says she has made their breakfast, but won't reveal where it is. Mario must use his 3-D flip to find it.
Here are the items earned after purchasing the packages:
It is notable that accepting the Star package is the only way to obtain a Slimy Shroom in the entire game, other than collecting 150 Shop Points.