This is such a fun and easy Garden Project, you can change it up with different words or pictures. I found myself a variety of skinny flat rocks than added a couple of coats of paint to the tops.
I added vinyl to the tops of the rocks but you could also use a stencil or hand draw something on.
For this one I found a rock that had a larger bottom on it but still had the flat surface so it could stand up on its own, then again added a coat of the blue paint and some vinyl lettering to the top.
This would also be a great project to do with the kids and see what they can create. I know my kids have spent many hours painting rocks.