One of the four stereoisomers, (1R,3R)- or (+)-trans-chrysanthemic acid (pictured), is the acid part of the ester pyrethrin I, which occurs naturally in the seed cases of Chrysanthemum cinerariaefolium.
Mosher's acid contains a -CF3 group, so if the adduct has no other fluorine atoms, the 19F NMR of a racemic mixture shows just two peaks, one for each stereoisomer.