The dilutions of the standard (BSA) to be used in Bradford assay for the standard curve should be between 5μg/ml to 100μg/ml. At least five dilutions of BSA standard will be required for the standard curve.
So, in the method section, you may write as follows:
“The stock BSA standard solution was prepared at a concentration of 5mg/ml. The stock was pipetted into a set of tubes to achieve concentrations between 5 to 100 μg/ml of protein per tube.”
Yes, it is common to report the concentration of the standards used in the Bradford assay in the methods or results section of a research paper. If your stock solution of BSA was 5 mg/ml, you could report it as such, or you could dilute it to create a standard curve with a range of concentrations (e.g. 0.1-1 mg/ml) and report the concentrations of the individual standards used. This information is important for the reproducibility of the assay and allows readers to compare the results of different experiments.