It is edible. And the blue stamens will turn pink if exposed to radiation and chemical pollution, so it is a marker of the environment.
It spreads pretty rapidly and can be hard to get rid of if you dont like it. I've been battling it in my garden for a few years now (formet owners did nothing to maintain garden and it was all over). It will come up from small bits of root that get left behind when you pull it.
The flowers are pretty though. If it starts to look leggy or ratty you can just cut it way back and it will regrow. It is pretty close to being indestructible.
Edible, really? I've never heard that!
It is a prairie plant, so there is a native variety here in Wisconsin -- not sure where you live.
Although it can take a couple years and some persistence to get rid of a mother plant, it isn't hard to control seedlings through weeding (in gardens) and mowing (in the lawn) -- at least here where we have serious winters.