I have bought fat quarters - and I wash them before I use them and they come out varying sizes due to shrinkage - but I just kind of go with the flow. Also I have bought packages of fat quarters because I am still learning how to put colors/patterns together - but then I am also still building my stash. I find that I cut the charm squares or less than I need from yardage and have learned to look at 1/2 yds or so.
Marysewfun