Rock! It's the most popular mulch for flowerbeds, for the simple reason that it's more or less permanent, and therefore the closest thing to a no-maintenance solution you can get for flowerbeds. If you like to do a lot of gardening with annuals, bulbs, etc, then consider wood mulch instead.
The customer wanted stairs through this retaining wall. These are time-consuming (and therefore more costly) features, but the result is a very nice look. And, of course, easy access.
The space under deck stairs is one of the most common sources of frustration for homeowners. It's not very functional: hard to mow or trim there (if the grass grows at all), and not enough headroom to make it a patio space. It begs to be turned into a planting area. Here's one I did that worked out very nicely. This was a southern exposure where direct sunlight shined under the deck, so it utilizes sun-loving plants. A northern or eastern exposure would require shade plants such as ferns and hostas.
-Before and after: This customer wanted a visual screen for the patio. There are various ways to do that: plantings, drop-down shades or curtains, or solid panels. This is an option I've used on my own deck. It's call Flex-Fence. All this company sells is the hardware to mount boards to create louvers. As you can see, this product allows the boards to open and close like venetian blinds.
The front corner of a house is often a frustrating area, especially if it slopes. A common solution is a retaining wall flower bed. This one illustrates the improvement dramatically. The retaining wall is a nice feature in and of itself, but it also creates a level planting area, keeps mulch out of the lawn, and hides an ugly downspout drain. An additional benefit is concealment of utilities from the curb perspective.
Many people really like the look of tree rings, in their own right. Aside from that, there is actually great practical value in tree rings. It's hard on trees when mowers and trimmers nick the trunk. And it's hard on mowers when surface roots make mowing seem like off roading in a fourwheeler. So put mulch around the trunk of the tree and solve those problems. Then put a ring of blocks in to keep the mulch where it belongs. The drawback is that roots grow and will, usually in just a few years, start to lift the blocks, requiring you to reset them. Doable, just be aware that tree rings don't stay put forever.
One solution for a chronically wet area is to create a dry creek bed. The photo is self explanatory. This back yard sloped in such a way as to create a trough, and the creek bed runs its length.
Timbers and ties make nice retaining walls. For a while. But you can see what eventually happens. Here, a simple block retaining wall makes a nice, and much more permanent, replacement.
Boulders are the most cost effective way to make a retaining wall, in many cases. Like any kind of wall, a poorly built boulder wall will eventually become unstable, but when done right they last indefinitely. And unlike a block wall, a minor amount of soil settling beneath it won't cause any visible gaps or cracks.