Flutter UI-Kit is a collection of real-world app UIs built with flutter. It consists of many templates which you can play with.
This app shows that how amazing UI can be created using Flutter.
Here are some of the resources you would like to see for learning flutter :
1.) Official Docs - https://flutter.io/
2.) Udacity Free Course - https://in.udacity.com/course/build-native-mobile-apps-with-flutter--ud905
3.) Awesome Flutter - https://github.com/Solido/awesome-flutter
4.) MTechViral Video Tutorials - https://youtube.com/mtechviral
5.) Flutter Example Apps - https://github.com/iampawan/FlutterExampleApps
6.) Awesome Dart - https://github.com/yissachar/awesome-dart
7.) Aqueduct Docs - http://aqueduct.io/