It sounds as if your lawn has been struck by fairy ring. This is a fungal infection related to mushroom (also fungus) infestations. The grass within the "ring" grows at an accelarated rate, then dies. this is what causes the dead circles in your lawn. Aeration can help control fairy ring, but it may be necessary to kill off grass in the affected areas with Roundup and then replace it.

If you have had plenty of water, the only two other reasons that grass turns brown is fungal disease or insects. You might dig up a full square foot of the sod somewhere where it is browned out looking for grub worms. They are about the size of your thumb and have a C shape. If you have more than a dozen in the 1-square foot area, then that's the problem and you can treat for grub worms. If you have a lot fewer, then the problem is disease. The problem with treating for disease with chemicals is that you have to figure out which disease it is or you'll get the wrong treatment. One of the reasons I started gardening organically is that the treatment for disease is usually the same: corn meal. Yes, ordinary corn meal (like what you cook with) grows a predatory fungus that kills the disease fungus. It takes 3 full weeks to work but it works most of the time. I see you have a mix of grasses and plants (weeds???) in the lawn. One of the excellent reasons to have a mix is that not all the grass or plants will be affected by any single disaster. You can probably leave yours alone and it will fill back in with something. You might consider sowing Dutch white clover seed over the entire lawn. It is a hassle free ground cover, especially when mixed with other grasses and plants.

Start fertilizing after you mow real grass, not just weeds, for the second time. If you had rye then the bermuda will come in a little late...like now. But it doesn't make sense to fertilize dormant bermuda. That's why you wait for the second mowing. You can use a herbicide like Weed-b-Gon or Weed-b-Gon Chickweed, Clover, and Oxalis Killer on it now. If you decide to overseed the bermuda please wait until June when the soil is hotter. By then you will know if you even need to overseed it. Bermuda is pretty self sustaining once you have it, so I don't think you will need seed. Watering: Deep and infrequent is the mantra for watering. This is for all turf grass all over the place. Deep means 1 inch all at one time. Put some cat food or tuna cans around the yard, and time how long it takes your sprinkler(s) to fill all the cans. Memorize that time. That will be the time you water from now on. My hose, sprinkler and water pressure takes 8 full hours to fill the cans. Your time will likely be less. I like gentle watering. As for watering frequency, that depends on the daytime air temperature. With temps in the 90s, deep water once per week. With temps in the 80s, deep water once every 2 weeks. With temps in the 70s, deep water once every 3 weeks. With temps below 70, deep water once a month. Note that you have to keep up with quickly changing temps in the spring and fall. This deep and infrequent schedule works in Phoenix and in Vermont, so it should work for you. The reason for deep and infrequent is to grow deeper, more drought resistant roots and to allow the soil to dry completely at the surface for several days before watering again. If it rains, reset your calendar to account for the rainfall.

The species you have is a tropical clumping bamboo whose scientific name is Bambusa vulgaris "Vittata": B. vulgaris "Vittata". It's commonly called Painted Bamboo. I've grown dozens and dozens of different bamboo species and I have to confess that I've never seen that particular ailment or appearance. I can tell you that the gray culms in the 3rd photo are nearing the end of their useful lives and I would prune them out at ground level (individual bamboo culms typically last about 7 years before starting to die off). I can't say what the splotchiness is from; bamboo do not commonly have diseases, but it could be a fungus. However, I also think you should be giving it more water and particularly not waiting to do so after you see any evidence of leaf curling. If you go to the link I included above, there are many serious bamboo growers there and re-posting your photos there in one of the forums might get you a more definitive answer about what is going on.