I need easy patterns for good chemo hats

[cnit]

Greeting from New York! The weather has been really lovely here.
I have been inactive for a while because I have been sick. I just found out I will lose my hair due to chemotherapy in about 6 weeks. I am a beginner and could use some recommendations for really easy hats that go over the ear a bit and provide good coverage for the head. I also would love to hear recommendations for non itchy fibers that hand wash well. Plus yarns that are cool for indoor use as well. Thanks in advance for your help and for all your help in the past. You are a great group!
Carol
PS I have a large melon, is it easy to make a hat larger than the pattern?