If there is a waterway between them like a river it might work in addition to the villages around Waterdeep. As only source of food? No way. Why would Waterdeep not be surrounded by farms like every other city in existence? Its much more practical.
Same goes if there is no river connection. Why walk 30 miles to your farms when instead you can have them on your doorstep. And bulk transport of goods without water before the era of combustion was hard and expensive. Especially food as everything you can use to pull the wagons with food (unless you are so high magic to use undead or golems) also needs to eat said food.
The other problem with Goldenfields (I think you mean that) is that a single settlement is supposed to supply multiple cities with food which is just not possible. Unless there is some amazing supermagical fertility enchantment there which quintuples the yield you get a single community, even with 5000 farmers all working their own plots, can't produce so much food that, after taking whatever they need to survive themselves, it can support even a single city as large at Waterdeep.
But Waterdeep is a bad example anyway as the population of 2 million for the area is just nuts and there is no way to feed so many people on such a small space without modern agriculture.