Hi! I am trying to prepare my garden for planting but last year I got infested w cabbage worms and now my soil is riddled with old egg casings… since it's been a year can I still reuse the soil w/the old shells/casings or do I need to scrap all this soil and rebuy?

Those are not cabbage worm eggs. Cabbage worm eggs are freshly laid on the leaves by white small butterflies.
I think they are Fertilizer pellet empties. Did you use timed release fertilizer?

I had tons of the little green caterpillars last year and thus a ton of the little white eggs. As I was checking out my garden box I noticed all those yellow casings which I assumed were those egg casings that had been dried out because I didn't use pellets or a times release fertilizer last year!

They really do look like time release fertilizer capsules. Maybe they were in the soil you used? Moths and caterpillars lay their eggs above ground, not necessarily on a plant but above ground.

My only other thought is they are snail, slug or worm eggs or some find of fungus.

Yeah maybe you all are right since there are sooo many of them in there so I'll recheck the soil I used and got from there!

Thank you!