Cool Discovery in the Garden

Yesterday as I was finishing up putting some organic soil in my flower garden when I encountered the strangest thing. I dug up a section of soil, and with it came a huge bee! This was seriously the biggest bee I've seen in a long time. It couldn't fly, so I managed to get it onto my shovel to take over and show Scott. Then I put it out on the grass. I went back to digging, and when I did, I found 2 more bees! Crazy! They were down under the dirt. I've never seen this before. That time, Scott was nearby so he came over and looked, and I ran in to get my camera. I am now trying to figure out what kind of bees these are. I think it's between a bumblebee and a carpenter bee. If anyone knows based on these photos, feel free to let me know!