I started my campaign there, but it's really based around the Lumber Corporation, Chelish espionage, interplanar conspiracies and Treerazer. It starts with a theft, goblins and a fire in a lumber yard and probably won't help you very much.
The only published scenario in Bellis is The Fellnight Queen, but that's 7th level and wasn't much use to me.
I had to flesh out the area quite a bit. From a strategic POV, Bellis is important but very vulnerable, being on a wide and indefensible river with a vaguely hostile neighbour and surrounded by Fey of no reliable alleigence. So it needs fortification, a series of watchtowers on the river, a land route west to the rest of Andoran and a bunch of local villages for farming, mining, logging, fishing and so on.
So there's a small castle on a bluff overlooking the town, a fort protecting the harbour and the usual walls. There are two sawmills (copy that from Sandpoint or Magnimar); logs either by the Bellis Brook (a smallish creek) or floated down the Sellen, roped together in rafts and are processed here.
Fields and farms surround the town (aside - have you noticed how fantasy films forget this? LOTR stands out here; what do the people of Edoras or Minas Tirith eat?).
Main road (starts as a half-maintained muddy track, gets much worse) goes W to Carpenden through a series of villages:
8 miles: Witlow. Small, boring
12 miles: Essenby. Big lumber yard, top end of Bellis Brook.
16 miles: Purford: Small, boring
20 miles: Tacken’s Bridge. Bridge over a river, toll. The inn is a fleabitten hovel - avoid. West of here it's not very safe, especially at night.
27 miles: Hazelford. Copper mines, ford, charcoal, hazelnuts
32 miles: Ridgefoot. Copper mines, ford, bottom of big hill. Dwarves maintain the road and have a toll booth.
35 miles: Barten: Fort and small town controlling ferry over Dragonfly River. Suspiciously excellent inn.
(the road continues, but I've not written anything)
Details aside, the point is that it's not simply an isolated town in the middle of nowhere. So you can set any adventure here if it fits with a river or forest, and even that's not 100% necessary.
It doesn't take place in Bellis, or even Andoran, but Dragon's Demand takes place in and around a smaller town that Bellis (388 people versus the 4,800 people Bellis is supposed to have) but it's a pretty fantastic level 1-7 module.