Spot the Frippet: trefoil.

 Four-leaved clovers are supposed to be lucky, but the three-leaved varieties are very beautiful, too:

birds-foot trefoil, photo by lawn weeds

There are lots of different plants with trefoil leaves, many of them members of the pea family, so I suppose that if there was no other way to spot a trefoil then you could always plant a pea.

Or look out for a Girl Guide:

one of the symbols of the Girly part of the Scouting Movement

This is another trefoil symbol, but of something even more dangerous than a Girl Guide:

warning sign of a radiation source

There was a fashion for trefoil windows in the 1800s:

or if you're stuck, why not draw your own?

drawing by AnonMoos

Actually, now I come to think about it, three is a lucky number, so who needs four leaved clovers?

Let's hope three is lucky for you.

Spot the Frippet: trefoil. This word comes from the French trifoil, from the Latin trifolium, three-leaved herb, from tri, which means three, and folium, leaf.