Download Simple UI Free Unity. 

This is a simple, but very versatile UI theme that will cover all basic UI needs for your game. This pack uses Unity’s built-in UI System, so if you are already familiar with it, then you already know how to use this pack! In addition, this pack also comes with several sample scenes, which will showcase different ways in which these assets can be used and help you construct your own UI.

This pack contains the ‘Simple Vector Icons’ pack, consisting of over 320 icons for your game.

This pack also includes the ‘Resource Vector Graphics” pack, consisting of several vector resource graphics.

The font as seen in the samples is also included and are licensed under the SIL Open Font License.