These I consider “art” crochet, where I get to make up the rules for myself. The common sense which I use to keep them flat is not sufficient. Stitching through the crochet from the back helps to remedy these problems, as does blocking, starching, and pressing from the back.
Inspired by the card on the rightI began this unintentionally small tablecloth. Some detail of a work in progress.
Much effort at flattening produced this. The edge of this is intentionally ruffly, because I liked the effect of the off-white motifs surrounded by green which ruffled into place. Altogether the effort came together.