Q.When to plant lily of the valley
I live in southwestern Pennsylvania and I would like to know when the best time is to plant lily of the valleys outside? Also, do they spread? Does the fragrance attract bees? Where do I buy them?

You should plant Lily of the Valley in the fall in most cases.
You can plant during the summer months and still have success, I transplanted several plants last summer that were gifted to me and had many flowers this fall.
Water well to get them established no matter when you plant them.
They will spread and fill areas in nicely.
If your local garden center does not carry plants try ordering them online.
https://www.gardeningknowhow.com/ornamental/bulbs/lily-of-the-valley/growing-lily-of-the-valley.htm