Oehlert (2000, Example 19.3) provides data from a small experiment on baking packaged cake mixes.
A data frame with 14 observations on the following 4 variables.
Baking time, minutes
Baking temperature, degrees F
Oehlert, G. W. (2000). A First Course in Design and Analysis of Experiments. New York: Freeman.
Weisberg, S. (2014). Applied Linear Regression, 4th edition. Hoboken NJ: Wiley.