I'm not familiar with MCKenzie so this may not apply to them specifically...
In general on wildflower shakers:
These may be bad news as some (but not all) contain invasive species you may not want. At best it seems that the majority I've seen contain a high percentage of annuals and few perennials. If that's what you want, that's fine, but do be aware and do some research on the species contained in the mix.

One thing I've noticed of late is that they have done away with genus and species names and have gone to genus names only, making it way harder for the average gardener to do research on the exact plant.

One example: listing only "chrysanthemum" on the label. Now that may mean Shasta daisy or it may mean Oxeye daisy. Hard to tell and that's exactly the point. Not that I personally want either but they are entirely different plants!! And it seems like it's a very convenient way to try to get around state noxious weed laws.

Thanks for the warning/info. I am near something in Ottawa called NCC land. With that said, I would hate to plant something invasive - plus, the neighbours may not be too keen on it. I'll pass. Thanks again.