Compost or manure.
Assorted drought-and-neglect tolerant wildflower seed mixtures.
To each bag, add one scoop black earth, one small scoop compost or manure, and a hearty shake of seed mix. Shake, or stir, contents thoroughly. Fold down bag tops carefully, decorate with appropriate illustrations and quotations, and distribute with love to nearby untended vacant lots, taking care to weigh the bags down with small rocks.
As the rains come and the bags disintegrate the seeds will, with the blessing, germinate and sprout.