Every year we go out and dig some grape hyacinths from a field on our property. They naturalize here and Larry found a patch the first year we lived here. I was amazed he found the patch because it's just in that one place. We can only find them when they are blooming; the rest of the time they look about the same as the green onions we have everywhere.
Larry is pretty concerned that we not dig up all of them, but I don't think we could get all of them if we tried.
The ones I've planted in flower beds grow well. They also seed into the grass. Since Larry likes daffodils in the yard, it seems the grape hyacinths are fine there, too.