This Interaction Farm can be used to quickly raise Gourdlets maturity to unlock more Parcels.

Gourdlets seem to have an Idle timer that makes them wait between interactions.
They need at least 2 tiles to move between or they will not consider interacting with anything.
They seem to be unable to move into a tile that has a Gourdlet performing an interaction in it.
Mailboxes and Recycle Bins have a very short interaction time.
Mailboxes have a side benefit of having a small hitbox on the post allowing you to mouse over Gourdlets a bit easier.