A pair of almost-free Shimano PD-7810 pedals. These are the best SPD-SLs ever made but people never service them as it needs a couple of unusual tools, viz. a 20mm cone spanner and a small circlip spanner. The water sealing is poor so they can often be rusted out if they were ridden in the rain.
Anyway, the LH pedal was perfect, with clean green factory grease, but the RH one smelt like an old steelworks when opened up and water has got in, leaving brown rust-stained grease. The vulnerable inboard bearing race has actually survived well, with no real pitting, but the balls have left stains on the raceways. A new axle unit can be had for only £20 now (plus £20 postage from the USA!) which is just about economic given that good PD-7810s can go for almost £100.