We discussed this in a thread some time ago, and I remember the “clean socks” thing coming up. The poster pointed out that a band on a long tour doesn’t necessarily have frequent or convenient access to a laundry. Putting in a “clean socks” rider is an easy solution; and I speak from personal experience when I say that putting on a pair of fresh, clean socks after you’ve been wearing dirty ones for a while (a month, in my case) is an exquisitely wonderful sensation.
Someone else there suggested doing exactly this! 
As for the brown M&Ms, I think that was Billy Idol’s band.
Martin Mull is only known today as an actor, but he is a songwriter and back in the early 70s, he put out a few albums. On his first album was a song “Margie the Midget.” His contract included a rider that any midgets attending the concert were to escorted to the front row and seated there.
So awesome. I think this means something, in light of the conversations in the Beyonce/megastar thread.
Back in my college days I worked for the concessionaire at a venue that hosted concerts. I was the one who set up the food and/or beverage order in the performer’s dressing room(s) and had to deal with these riders.
I had responsibility for the food and beverage but had absolutely nothing to do with the setup of the stage, lighting, or sound systems. I did my job properly but that in no way should imply that the electrical people did their work correctly, and vice versa.
Most riders specified exact setups including brands of beverages and the manner of service. Typical would be 6 cans of Coke (NOT PEPSI!) on ice. 12 bottles of Dasani bottled water at room temperature, with a bowl of ice and 6 drinking glasses (Glass, not plastic!). And so on…
It was the rare one that left anything to my discretion. I remember one of those rarities asking for a six pack of bottles of a locally produced lager. I got to go to the liquor store and pick and choose.
None of the requests were particularly weird. No picking out brown M&M’s. But we certainly catered to the personal preferences of the performers.