I like to picture rock golems as just a combination of smaller rocks
In this picture, I took a small rock and stacked it on itself to make a golem like shape. In an actual piece, it would be best to use different rock shapes. In the edit, the procedure I used was to block out shapes and then fill in from there like in this piece from cure
but I suggest doing that only if you have an idea of what the golem will look like in terms of shapes. Try to draw it out on paper and sculpt it up from smaller pieces. gl!