So I went with a mixture of kitty litter (that's the best I could do in the clay department) for clumping purposes, composted cow manure (yes, composted - it's less stinky, at least while making the bombs private LOL there between me and the bombers), sunflower seeds (easily found in big bags in the birdfood section), and some yellow clover seeds (for variety).
Mixed it all up with some water...
Seed bombs were tossed here in the Woo on May 1st. We hit 3 vacant lots. It's been off and on lightly rainy for a whole week and the seed bombs were semi sprouted by the time we tossed them, so fingers crossed that something comes from it and perhaps you'll see some blooms in August!
Or maybe we just had a great time making snack bombs for the city wildlife.