Workers are building specific, you can't put a mill worker in the dairy or a bakery worker in the mill etc.
The only worker you can put in the pasture is the cows, they show up at the bus stop like all the others!
Look at the icon on the worker's info screen, it shows which building they can go in!
Everything you need to know about getting new workers can be found here
For all your gameplay questions you can head here and find the topic you're looking for!
You can also check out our fan page, https://www.facebook.com/BFGrassRoots There's tons of awesome BUDS there that are eager to help neighbors and improve the community of the game!
If you're still stuck after reading the help center entries we'd be glad to walk you through it! email us at email@example.com