Did you mark your Spark with owner info?

[Blue Baron]

Where on the Spark is the registration # that TagMyDrone wants?

TagMyDrone requires prior FAA registration. SafeDrone doesn't require prior registration. So, TagMyDrone is NOT the US flavor of SafeDrone. Yet to come, I guess ...

 

[peejay]

I've put text file on memory card and I labeled my sparky on the side, and on the batteries itself [in case some kind of "let's fall apart in mid-air" scenario ]. phone number, mail and the "do the right thing" slogan. Casey-style

 

[Zinful]

I have a sticker on the outside of all my batteries that gives my name, address, and phone #. Plus I have numbered all my batteries to help in rotating them.

 

[Soarmax]

I have my phone number and an offer of reward if returned.

 

[f00f]

Just FAA registration number written on the hind legs of both my Spark and Mavic and inside the battery compartment reg# + basic contact info (name, tele, email).

As others have noted, in the USA the FAA reg is not required for hobby pilots if operating strictly under the "special rule for model aircraft". For reference, current verbiage is listed here:
https://www.faa.gov/uas/getting_started/fly_for_fun/