Cover your worksurface to protect it from dirt and spills. Line a baking sheet with newspaper.

Break off a bit of clay and roll into a ball. Use your thumb to create an indent, and insert a pinch of soil, followed by a pinch of seeds. Seal the indent and re-roll into a ball. Repeat with remaining clay, soil and seeds. Let clay dry for a few days, turning the balls if you like (next time I might set the balls on a wire rack so that air circulates on all sides).

Once dried, place a few balls in each envelope, along with instructions, and tie up with a tag and some twine.