This is a Start Menu icon. We've made it in iOS style, first introduced in iOS version 7 and supported in all later releases up until now (at least iOS 11). This style is based on thin two-pixel lines and is optimized for 50x50 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 12,600 icons, all in the same style and quality.
The icon Start Menu starts with a horizontal rectangle on the bottom with a filled in circle to the left, inside. There is a wide vertical rectangle, with two vertical lines towards the top, sitting on top of the bottom rectangle, on the left side. There is a thinner vertical rectangle right next to the other vertical rectangle with a small line at the bottom.