It sounds like your soil is very similar to what we have in our yard. Have you thought of using Hosta's? They grow very well and require almost no maintenance - just cut the dead leaves down to the ground in the fall.
There is a huge variety of them, from 8" wide/tall to about 30" wide/tall.
There is a huge variety of them, from 8" wide/tall to about 30" wide/tall.