This may be well known by now, but I didn't see anything on this so thought I'd share what I've got.
For those trying to attract bees in the Sonoran desert, I thought it might be of interest to note that the long stalks that grow from various agaves here when they flower are great to leave on after they've died and started to dry. Carpenter bees like to use these for homes, so you've got a built in bee home with it.
Also of interest is that the majority of bees in the Sonoran desert are singular rather than colony bees. They typically burrow into the ground or create nests inside dried stems or abandoned tunnels left by wood-boring beetles. So along with the dried stalks from agaves, various types of dirt and dirt structures in the yard can attract bees. When I ended up making small dirt 'walls' just a couple inches high, I witnessed numerous bees burrowing in to make homes for their offspring to emerge from the next year. Right in my garden - very useful!
I'm still trying to learn about what varieties of dirt attract which bees, though. But just an interesting thing to note that in the desert, even our bare, not-good-for-growing-things dirt can have a purpose in supporting the whole system.
Although if you raise honey bees, these tend to out-compete the native bees and drive them away.