Eggshells are good, if you are going to grow tomatoes. Tomatoes that don't get enough calcium get something called 'blossom end rot'. I crunch the shells up, so they are small pieces. (But I don't have bears near me, so I have no idea if crunched up shells would attract bears.)

I have not done it, but I have read about vermiculture (composting with worms). They said the worms like coffee grounds (but you have to feed them more than that). Worm casings are excellent for the soil.

Re: ash; Ash can change the pH of the soil. And plants definitely have a pH preference. So if you've checked your soil's pH and it is low (more acidic), then ash is good for raising the pH and adding calcium and potassium, both good for the soil.