I was very fortunate to observe a female wool carder bee anthidium fabricius collecting fibers from the underside of Lamb's Ear leaves.
These bees scrape the hairs or fibers off the surfaces of leaves into a ball and carry it back to their nests where they stuff the balls of fiber into the nesting cavities. Then they form a loaf of pollen in the soft mass and lay their egg on the pollen loaf. Then they continue to fill their nesting tube with a series of these soft brood chambers.
I filmed two videos of the female wool carder bee I observed. I wish the picture quality was better, but it still is very interesting to observe the bee in action. In the first video she forms one ball of fiber. Then, surprisingly enough, in the second video, while carrying the first ball of fiber, she scrapes fibers off the underside of another lamb's ear leaf to form a second ball.
She then flies away carrying two soft balls of plant fibers.