It appears that your house is plaster (stucco) for siding? With other siding like wood or vinyl you can see where the foundation of the house comes together to the framework (wood). It is a very bad idea to put any type of flower bed (soil or mulch) any higher than that point where the wood starts. This will bring in rot or termites. With stucco it can be difficult to see that spot. Some homes have deeper crawl areas and tall foundation walls, but other homes sit practically on the ground. Those are usually older homes.