You are looking for a dollhouse. In Discounty, the rats at the pier want a tiny home they can claim as their own.
Giving them that item completes the pier step of the Vermin Ties quest and unlocks another fast travel point in Blomkest.

You need a dollhouse, and Barbara points you toward that answer once you reach the harbor rats. If you have already spoken to the relevant NPCs and checked the right area, find the dollhouse, place it at the pier, and the rat group will accept it.
The Direct Answer For The Pier Rats

The Item You Need Is A Dollhouse
The pier rats want a dollhouse, not food or waste. Barbara hints that they may want miniature furniture or a place to call home, which matches the rat-sized setup at the docks.
Where To Place It At The Harbor
Head to the southeastern edge of the Harbor, near the pier and docks area. Place the dollhouse where the rat group is waiting, close enough to count as their offering, and the quest state will update right away.
Why Barbara Points You Toward A Home
Barbara gives you the idea that the rats want a home, not a snack. This clue sets this puzzle apart from the other rat tasks around town.
How To Get The Dollhouse

Check The Antique Store Inventory
Check the antique store, where the dollhouse can appear in the rotating stock. Once you spot it, buy it and bring it to the pier rats.
Solruna And Rotating Stock
If you keep up with Blomkest errands, check the store regularly while moving through your day. The item does not always appear on every visit, so it may take a few checks before the right toy shows up.
What To Do If The Dollhouse Is Not Available Yet
If the dollhouse is missing, keep progressing through the game and return later. Daily inventory changes mean the solution can appear after a bit more story progress.
What Usually Stops Progress

Speak To The Relevant NPC First
Some players try dropping items before talking to the right character, which usually causes confusion. For the pier rats, Barbara’s dialogue matters, so make sure you have heard her hint before you try to solve the offer.
Story Progress In Chapter 3
The rat quests tie to story progress, and some steps do not open until later chapters. The broader Vermin Ties task begins in Chapter 2 and continues onward, while certain triggers depend on later progress.
Placement Mistakes Near The Sewer Grate
If the dollhouse does not register, check your placement spot. Set the item where the game expects it near the rat group, not just anywhere along the shoreline.
How The Pier Solution Fits The Bigger Quest

Other Rat Requests Around Town
The pier step is part of a larger chain of rat puzzles across Blomkest. You work through different areas and solve each group’s clue.
Each success opens more of the town for easier movement.
The Recycling Center And Cheese
One group near the recycling center wants cheese, which fits the rat theme. That step uses a food dish by the dumpster and ties into your growing trade options.
The Bus Stop Group And Fishy Waste
The highway rats near the bus stop want fishy waste, which comes from Barbara’s fish stick operation. Barbara connects you to what the rats actually need.
Karl The Farmer, Sheep, And The Farm Bowl
Karl the Farmer, sheep, and a bowl on the farm form another group.
Town errands, story progress, and unique offerings all blend in this quest line.
Aunt Tellar and the hardware store add to the network of tasks you complete.