After you get the invitation and the pen, Charlie Brown and Snoopy are in his backyard, on the far left of the island. You will play a mini-game as Snoopy gathers some leaves in a very relaxed manner.
The name of the island is Great Pumpkin Island. See the related question below.
"It's the Great Pumpkin, Charlie Brown" was first aired on television in 1966.
Charlie Brown awaits the arrival of 'The Great Pumpkin' .
The Great Pumpkin?! that's from charlie brown.
Snoopy
No.
On Great Pumpkin Island, Snoopy and Charlie Brown are in front of the pumpkin patch, searching for the Great Pumpkin. They are part of the Halloween-themed adventure where players help them navigate through various challenges to find the mysterious holiday figure.
linus
Rocks
To get to Charlie Brown's backyard, go left past the Flying Ace cafe. You need to complete the pumpkin patch first, then get the pen and invitation, before you can do the Snoopy and Charlie Brown scenes. (see related question)
After Linus mails his letter, go left to where Lucy and Charlie Brown have the football.
He is with Snoopy in his backyard, but only after you have gotten a pumpkin for Lucy, a bag for Pigpen, and a lemon sucker for Linus.