I have a garbage can under my kitchen sink, you may have one in the same location.

If you want to go through the hassle you could try to sell them (or give them away) on ebay or craigslist.

Wish I had a garbage can under the sink, but the sink isn't connected to water yet. ;-)

Was actually hoping someone would say they had some use for them.

"The cord in question is inside the wall..."

Cordage is not allowed inside walls.

Concealed wiring in walls must be an electrical code approved wiring method, ad NO flexible cord has this approval.

Now I had to go look up exactly what that cord is:

{{!gwi}}
25' Black Power supply lead for LED connection of 12380Bk to 12382BK. CL2 jacket suitable for run behind walls (please check local electrical code for compliance) U.S. Patent Pending

Except ours is 10', not 25'. This is one of the few parts of this job we hired out because because between the two of us we really don't have the expertise to do it well and safely. It wasn't just the undercab lights, we also added in 7 recessed lights, moved the ceiling fan, moved outlets/switches and added outlets/switches. I'm big on DIY, but not that big.

Class 2 wiring is approved when being used with current-limited devices such as this.

Lighting rarely has a low enough current to meet the signalling rules.

"please check local electrical code for compliance"

that is a HUGE red flag.
Dir you chec

actually LED lighting doesn't draw squat so each run is usually under 60VA

If they are rated FT1 or FT4 they are ok aren't they?

Sell or give away the plugs on Craigslist, Kijiji or Freecycle.

or offer them to whoever it was that did your job.