<human>: I recently ended my employment with a company after realizing it wasn't a good fit for me. The owner (my boss) is now refusing to pay me the salary detailed in my offer letter.

 I initially received an offer from the company offering to pay me an hourly rate for only the hours I billed. I replied declining the offer. The owner emailed me back asking what it would take for me to accept the job. I told him I would need a guaranteed salary that I was not willing to take the instability of hourly work. He replied with another offer letter that guaranteed a base salary and additional compensation for every hour I worked over 40 (per week). I accepted the offer and started a week later. Now that I'm no longer working for him he is trying to only pay me for the hours I billed (40 for the entire month I was there). This was my concern which is why I only accepted the job with a salary guarantee. When I asked the boss about my offer letter he responded saying that I won't be receiving it as I didn't work a full month (ie: didn't bill on weekends), that I started in the middle of their billing cycle (I started on Monday June 2nd) and that I took a day off. He claims that for the above reasons I will only be paid for what I billed. 

I have everything documented, including proof that I started on June 2nd and stopped on June 30th. If I take him to small claims court do I have enough to stand on?

Summarize the given text in a few sentences.
<bot>: Former boss won't pay me what was in my offer letter. Can I sue him with the offer letter as evidence?