Loretta suggested some Underground Railroad blocks for your traditional block sampler quilt. Go to your public library and try to get the book Show Way by Jacqueline Woodson. It's a Newbury Honor Book and will be located in the children's section of your library. It's a picture book about several generations of black girls from the same family growing up as slaves and then free. But they all learn to quilt from their mothers. The patterns that they use are all traditional patterns and the pictures are wonderful. On some of the pages, the blocks are named for you. It will definitely give you an idea of what blocks were supposed to have been used.
I do not think that these quilts were used to guide the way for runaway slaves on the underground railroad, but the idea of how they passed the block patterns and quilting skills down from one generation to the next is really interesting.
Connie