sedums. You can get seeds from, among other places, Stokes

the link takes you to low growing, matting types which won't grow over 6" tall. Alternately because sedums grow quickly anyone who has some in a garden will likely let you have some. You just tear some out of the ground and kind of push it down,step on it to make contact with loose soil and it takes off.

Alternately you can buy steppables which is a line of plants (not seeds), but they are all rated according to amount of light, water, foot traffic they can take etc.

If you choose sedums from seed then for an idea of how to sow them you can read the cultural info at stokes, but I used one packet per tray (standard nursery tray). If I were sowing outside I would probably not sow so closely.

Keep them moist until germination and first 'true' leaves. After that they become pretty carefree except during extreme droughts., but the drought would have to be quite extreme.

I have the same problem. Thinking of trying Mentha requienii - Corsican Mint. Low-growing, mat-forming, lovely smell, hardy to zone 6b, so should be ok for our area. Haven't found a seed source, but I think Bluestone sells small plants.

Best,
Jen