Bee making a nest in a post with petals July 16th 2020

We happened to spot this Bee come back and forth with tiny petals and placing each petal into the hole it had found in a post in our garden fence. It flew off and then came back every thirty seconds or so, with a new petal. After a while it stopped and then we spotted it later with different coloured petals. We managed to capture this unexpected surprise on our two phone cameras, so the quality and format vary, but at least you get to witness this rare phenomena, which was, we discovered about 2010 by scientists.