"What is it?" Wednesday - Purple Flowers

I have a ton of these plants growing in the yard. There's even some bees in the photos:

This blooms all June and is quite popular with the bees and butterflies. If you want a hint (scroll down)
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... it is also quite popular with Monarch butterflies.

What is it? Think about it and I'll post the answer next week.

Last week's answer to:
http://ohiopoisonivy.blogspot.com/2014/06/what-is-it-wednesday.html

This beautiful yellow flower is commonly called Bird's-foot Trefoil  or Birdsfoot trefoil (Lotus corniculatus). It is a perennial that grows mostly in the Midwest but can be found over much of the continental US and Canada.  It has become invasive in some areas of North America and is considered especially problematic in the prairie and grassland regions of the Midwest.

Here locally in Columbus, it is common along the edges of the woods at the park I frequent. It's a beautiful contrast to the green of the woods.