Alfalfa pellets (horse food from the feed store) are a great amendment and have a fair amount of nutrient value in the nitrogen category as well. They feed the microbiome in your soil pretty well and encourage worms.
Worm castings if you can get them are a good plant food.
But, be aware that you will have to work at least twice as hard to nourish your plants if you don't use bought fertilizer.
