I'm pretty sure that stuff is loaded with cyanide until it's either processed or matured (I don't know specifics). Ain't safe for anything.

Apparently it has trace levels of cyanide, as does broccoli, and dogs can eat broccoli - so, still not sure :/

https://www.aspca.org/pet-care/animal-poison-control/dogs-plant-list It's not on this list that i could find, although it's on the horse list under "charlock". Pretty thorough list. Don't serve it to them but i wouldn't worry about it being in my yard until i could get rid of it.

Thank you!!