I was hit at a stoplight ( rear ended) went to the hospital was diagnosed witha concussion.now have documentation that the accident caused

It sounds like the insurance company is trying to get you to agree to a quick and almost certainly low settlement. Do not sign anything without first consulting an attorney.  The value of your case is typically determined by looking at the medical bills that you have incurred, future medical bills that you are likely to incur, any lost wages that resulted from the accident, any ongoing health issues that you may deal with as a result of the accident and past and future pain and suffering resulting from the accident. Insurance companies commonly try to settle these cases very quickly before an individual has a chance to really evaluate the extent of their injuries or speak with an attorney. Please let me know if you would like to speak about this.  Thanks,Jon