My nephew worked in a restaurant, and had the wisdom to save a couple of dozen plastic 5-gallon oil containers from the dumpster. I've inherited these, and I want to make a sort of "patchwork quilt" with them.

The idea is that I will cut the top & bottom off of the containers (which have a square shape), and bury them in the ground up to the top edge (with about 1/2 inch showing above ground before the mulch is applied). Then, I want to fill them in a patchwork-quilt pattern with different ground covers and other similar plants, in a wide range of colors and textures.

All of these plants should be low-growing (a foot or less), flowers are great, but not essential, and they should spread by root or runners. Also, this is going to be in dappled sun/mostly shade, so the plants have to be okay with that.

So far, I have several kinds of mini Hostas, pink and white Lily of the Valley and wild ginger that I can use. I am thinking of using about 4 of the squares with gravel or colored landscaping rocks or river rocks in them, and some sort of little sculpture or other item in that square. I'm also thinking about a larger item in the middle square, maybe a short bird-bath or gazing ball (although I think most of those are corny).

The "quilt" will be at my mother's house (where I have "my" garden), and I am in college full-time, out of town, and only have summers (not always guaranteed) and some weekends to attend the garden, so it has to be low-maintenance. We can do annuals in some of the squares, but getting them planted might be a trick. And spring bulbs are a nice idea, but what about when they finish blooming?

One more "hitch", I'm in the crack of zones 3/4, so it's gotta be hardy! I'm looking for about 6 more plants that I can include in this. The more interesting, the better!