Can I use the cash method of accounting?

I have a quantity of items I bought in 2017 then I ended up not needing. I sold some of them during the 2017 year and made a profit. 

This is not an official business or anything, but I am making a profit from selling these items and I do plan to sell some other things moving forward (more as a hobby, I still have a full time job)

I'd prefer to use the cash method of accounting and just note how much I bought them for, my expenses, and my profit as opposed to using inventories.

Is it ok/legal for me to use the cash method of accounting in this situation?

Thank you. I just want to make sure 100% before I move forward.