The world famous Fisher's iris set: 150 flowers from 3 species with 4 attributes.
data(ep.iris)
ep.iris$data: Data matrix with 150 flowers (rows) from 3 species with 4 attributes (columns) describing sepal and petal features. ep.iris$design: Design matrix with 150 flowers (rows) with 3 species (columns) indicating which flower belongs to which species.