What is this?

My son tidied the front porch over the weekend. We have "bouquets" of branches flanking our front door -- the kids cannot leave a hike without taking something home. A seed pod, a feather, lots of rocks, you get the picture. Many of our branches are leftovers from beavers. Some are actually roots, not branches. Some are really cool looking. But what is this that he found?

I noticed recently that a couple of these things appear to have the thread intact but the bulb is broken. Makes me think that maybe these things are pupae. Even spacing, time of year, hmmm. It's a mystery.