2 years back I processed a whole bin of Sierra wireless cards from late 1990s. I rarely get the yields others do on this site, but I can get within 20% most of the time. So take my numbers with that in mind. The cards I ran look like this:
I didn't record the weight of the cards at the beginning. After I pulled all of the metal housing off, I had 14 lbs. of green boards. I trimmed the little - and I mean little - fingers off the PCMCIA connectors, and then cut out the processor which is under a black blob of plastic. I put the connectors flakes into AP and pyrolyzed the processors. I sold the board remnants and metal casing to an e-recycler locally for almost $13. The total gold I recovered was .82 grams or slightly less than .06 grams per pound.
Needless to say, I don't process these anymore. They go straight the the recycler.
Apparently, some ethernet cards can be used in old Amiga computers. I've sold a number of cards for $10-$15 each. Only drawback is that you need the dongle for some cards, so if it is missing the card is worthless.