Strange seeds

Hello everyone

Recently my dog got very sick and upon further inspection of his vomit and poop, I’ve noticed he has eaten some of these seeds that I’ve never seen before.

We’ve been living in this rental for a few years now, it has a few small bushes in the back yard and I’ve planted some flowers and things that are dog friendly to make it look less like a prison. I’ve gone over each plant thoroughly and can’t find the origin of these seeds. I found a few lying around randomly in the back yard so I assumed maybe birds dropped them off.

Can anyone identify what these are? A google image search has come back with zero results. Just want to know if my boof head is feeling unwell from these or something else.

He’s already been to the vet so that part is all sorted, just trying to do a home process of elimination kinda thing.

Thank you!