twill tape

Several groups made knit, crocheted, and quilted lap robes for the patients in the VA nursing home where my mother lived several years ago. They all seemed to use twill tape to label their gifts. Several put the organization name on them, some both org and maker's names. At least one donor provided two tapes so that the recipient's name could be added so that when it went to the laundry it came back to the right resident. This was particularly welcome because some people became very fond of theirs and if your shawls are going to an institution of that sort I recommend it.

If you wanted something inexpensive to match the color of the shawl, you could use any solid medium-wide ribbon. With either ribbon or tape you can cut to the desired size and the long edges won't ravel. Either is easy to write on with a permanent pen.

Of course, you can order printed labels, but tape and ribbon are inexpensive alternatives.

One suggestion: place the label somewhere other than centered at the back of the neck. Labels there make some people very uncomfortable and they might end up getting cut off and trashed as a result.