The most obvious guess would be 'bay leaf', but this already appears in the list of spices. Pichon et al. could not identify it. Lores is not actually used in any recipe in Le Viandier. One possibility is laurin, meaning 'wild thyme' (Godefroy, Montagne, Grieve). Another possibility is luce, short for fleur de luce, meaning 'orris root' (Grieve). An early English spelling for orris root is 'ireos' or 'yreos' ( OED), so perhaps a mis-writing is involved.

ventral to the forehead and supercilium, extending from the narials, if present, to the eye, bounded below by the rictal bristles, if present, and posteriorly by a line from the angle of the gape to the anterior point of eye.

tiny feathers or skin between the eye and bill of a bird