Here are some examples of different garden walls.

Some are dry stack, some are rock and mortar, some are other materials.

Culvert under the rock wall makes a nice crossing that looks a lot better than concrete. - grid24_12

This wall is acting as a retaining wall on a creek crossing.

rock wall with cement and wire behind it. No cracks! - grid24_12

This is a conventional mortar rock wall.

in a rock wall anything can be used as long the cement sticks - grid24_12

Sometimes you run out of rock, there's always broken bricks and concrete.

Native California grape, Vitis California crawling over a rock wall - grid24_12

A Vitis california is growing on the rock wall.

Dry stack wall, big rocks at bottom - grid24_12

Here's a 20 year old dry stack wall. Not well executed, but still up.

barbecue built into rockwall - grid24_12

Here's a barbecue that was inserted into this garden wall. You can buy inserts like this in many of the stores that sell brick.

No it;s not a pile of rocks. It's a dry California garden with two rock walls and some steps. - grid24_12

wooden steps set into rock wall - grid24_12

If cement will stick to it, you can use it in your garden wall. Now wood doesn't stick, but if you leave the screws sticking out an inch, they do stick.
This has a steel base for the hand rail riser that the little wall was built around.

setting sun on a dry stack wall - grid24_12

This rock wall is about 3 foot tall. Some of the rocks are only a couple inches across. But it's still there.

If you frame the edge of a concrete pour (like a patio) and place rocks against the form as you pour the cement you can make a low rock wall. Pop the forms as soon as the cement sets and wash the rock face to make a nice wall. - grid24_12

A step made up to a concrete patio. Form patio like your would normally, set rocks against the form with flat side against form, after you've popped the form(cement not cured but holding together) carefully wash out the cement between rocks.

rock wall with two bird bath and a little bird pond - grid24_12

Bird bath with pool on bottom.

Change the grade around an oak and the oak dies. This one died in about 20 years. - grid24_12

This was a pretty good sized Coast Live oak. Beautiful wall, dead tree. Do not change grade around trees. Leave the area under the tree alone. If you look up and see leaves, you are under the drip line.

changing the grade next to an oak tree kills it - grid24_12

This wall killed three full sized oaks. The people are gone, but so are the oaks.
I didn't do it! The combined iq of the people that did this is lower than our average daily winter temperature, in Celsius.

Short sections of railroad ties make good steps within the dry stack walls. Either drive some nails into the bottom of each and cement them into place or drill a couple of holes through them and drive a piece of rebar through them. - grid24_12

Railroad ties work well. Use some nails or screws hanging out the back to anchor the steps, or drill two holes through them and drive rebar into the ground.

Concrete steps out of broken concrete - grid24_12

Sometimes you have a bunch of broken concrete. and you need a wall or steps.

broken concrete path and steps - grid24_12

Broken concrete used as a step and as a patio.

I had to use a dolly to move these around. They made jim dandy steps.

concrete rock steps forming a sideways rock wall - grid24_12

here are rock steps built into a garden wall.

a 80 year old rock wall with some of our children - grid24_12

This old mortar and rock wall is about 80 years old.

Here's another of the walls that were made in the 1930's.