"They also serve who only stand and wait" is from a poem by Milton. According to the OED the l in almond is indeed silent. It is pronounced ahmond, although I don't know many people who actually do drop the l. Another interesting one is "different as chalk and cheese". It actually derives from the pastureland in my home county of Wiltshire. The north of the county being blessed with lush pasture providing excellent grazing for dairy herds, while the south, where I come from, has a few inches of topsoil with solid chalk underneath, & the grass is good only for sheep. Obscure or what?