Lancaster / PA Dutch ?
this is kind of hit or miss, but sometimes you can get a real-deal penn meal in the country cafetria, which is inside building #1 of the friday-only market called green dragon. even if it is a miss day, there are enough other food sources there to create a nosh meal.
the average meal will set you back 5 bucks, plus exactly 61 cents for coffee.
I think the days of getting authentic PA Dutch food in this area are numbered. There are very few places that I know of that haven't become commercialized and the real recipes have been forgotten. I would suggest Shady Maple, Good N Plenty and Plain & Fancy for a buffet type meal that you will not have to get dressed up. I personally would stay away from Millers and Hershey Farms. Dutch Haven is a good place to pick up a piece of authentic shoofly pie. Good luck and enjoy your stay, but please be respectful of the Amish and keep your distance when taking pictures.
The Country Table in Mt Joy is pretty good. Good baked goods. Krieder's on the Manheim Pike isn't bad. You can order ice cream sundaes with the buffet. My kids love both these places. Your Place on the Lincoln Highway has great stromboli, and also does country food as well. They have a lunch buffet during the week.
If you like BBQ, Hess's or S&S Grilling are good places that the locals (Amish & Mennonite included) really enjoy.
If you like traditional Amish food, try one of the firehall dinners. You can get turkey, ham, chicken pot pie, pork and sauerkraut or whatever made by Amish men and women at the firehall dinners but not all selections at the same time...one only. Usually sit family style and pass the food down to the rest at the table. In particular, Goodville, Churchtown, Kinzers, Bird in Hand, Leola, and White Horse all have wonderful good dinners. Here is a mention of the White Horse pot pie dinner:
A meal usually comes with the main course, vegetables, home made bread, butter, apple butter, beverage or coffee, and dessert. You get great food, as much as you can eat, and you are supporting your local fire department.
Schedules vary for each firehall. Dinner is usually a Saturday afternoon and evening.
Or you can try the Mud Sales, another fundraiser for the fire departments in the county, but the meal will not be sit down like the firehall one. Quick food.
Best of luck!
I will second The Country Table in Mount Joy -- it's where I go when I crave Grandma's cooking and you will find it filled with locals, no tourists. If you don't want to trek that far west (although it's easy to get to off of Rt. 283) then consider The Lititz Family Cupboard at the intersection of Rt. 501 and Newport Rd. north of Lititz. They will have a small buffet, but just order off the menu. Another option is Oregon Dairy off of Rt. 222 on Rt. 272. Also very popular with locals, though IMO, not quite as good as the other 2 options.