All types of farthings of Edward I used to be at least scarce. However, this was before detectorists started to dig them up quite regularly. Some types are still scarce or rare, whilst others are now fairly common.
Pictured here is a decent looking Edward I farthing, which was found by John Lashmar. On the obverse the bust of the king reaches to the edge of the coin and the legend reads E R ANGLIE. On the reverse the legend reads CIVI TAS LON DON. The class is 4de, which is very scarce.
The obverse has been struck off centre but the coin is otherwise in good Fine condition. As it isn’t one of the more common types, this Edward I farthing should be worth £50 – £60.