Seed balls, also known as earth balls or nendo dango (Japanese: 粘土団子), consist of seeds rolled within a ball of clay and other matter to assist germination.
They are then thrown into vacant lots and over fences as a form of guerilla gardening.
Matter such as humus and compost are often placed around the seeds to provide microbial inoculants.
Cotton-fibres or liquefied paper are sometimes added to further protect the clay ball in particularly harsh habitats.
An ancient technique, it was re-discovered by Japanese natural farming pioneer Masanobu Fukuoka.
https://en.wikipedia.org/wiki/Seed_ball