The Lowes garbage blocks are designed for people who think trees need to be blockaded in with little tree rings. They're not really designed for significant retention or structure. I wouldn't feel great about it. Do you have stone yards in the area that sell pavers and retaining wall block? I assume that's also where you'd be getting your pavers. There are some "economy" brands of interlocking wall block, and I'm seeing that the smarter yards are now selling wall block by the piece for smaller projects. If you're using CMUs (technical term for cinderblocks), you need to dig a footer to frost depth, pour a 4-8" footer depending on specifics, and then build your wall with the CMUs, using mortar and rebar. If you attempt to just dry stack them on a gravel base, there's nothing holding them together. You'll create a failure point for your patio. I spend my life in a lot of backyards, and where a patio rests on, or is supported by, a retaining wall - that's a common failure point. Overbuild it. Trust me.

I'm a big fan of wooly thyme. Elfin thymes, Irish moss and creeping phlox are nice, too. Some miniature sedums might look good... a few will tolerate occasional light foot traffic, and they are very drought tolerant. Corsican mint does not like too much sun, but it is extremely low-growing and smells wonderful when you walk on it.

One of the low-growing Sedums/stonecrops might be good for this purpose. It is fairly slug-resistant. Many types will be fine in your clay soil fill, and many will do well in afternoon sun. Gold Moss sedum (Sedum acre "Aureum") might work well for you as it is very low-growing and will tolerate moderate foot traffic and full sun. Likes a dry soil, and likely will be evergreen for you in Zone 7. We have Wild stonecrop (Sedum ternatum), which is a U.S. native in our rocky areas, but this stonecrop does better with some shade. Some sedums can get slippery if stepped on directly if they are tall/long, so if you go with a sedum, be sure that it's a very compact, low-growing one that will not send out long shoots over the pavers. See the link below for a fabulous sedum/stonecrop general website that has photos of many, many varieties of sedum. It's the one plant I can think of right now that is slug-resistant, tolerates afternoon sun and clay soil, is low-growing, foot-traffic tolerant, and disease and pest resistant. You wouldn't have to water it excessively so that's always a plus too. Here is a link that might be useful: Sedum Photo gallery

I don't really know how it works under heavy rain conditions. After rising the corner that gave me trouble now I am waiting for the stars to allign (that means a weekend without rain) so I can fill the joints with sand and run a plate compactor over pavers. (is this OK if I do not cover the plate with rubber?) Only after I am done with this I will have to see how it works under rain conditions. For now I am covering everything with a tarp because I did not put the sand in yet. Before the lowest point of the patio was on the opposite edge and there I had cement between the wall and the bricks. It did not help... i would like to slope the last line of pavers (this line is parallel with the concrete blocks) in such a way that it will form a channel See the "blued" brick below