Here is a collection of low poly rocks I made. 

They are procedureally generated so all should be slightly different. 

There is one plate of mostly round rocks and another plate that has flatter or more rectangular ones. Print whichever or both. 

They are around 25mm in the largest dimension, so scale up or down as you wish. 

You can use them as props for CyberBrick toys or for your miniature terrain, or anything else :)