Welcome to Mudcat, Katie. Here's hoping you join us.

Joe Offer listed this in his index of Sing Together, A Girl Scout Songbook. (Click on the blue underlined words to see it). I found that by searching Mudcat (in the search box at the top of the messages list for the lyrics "lord's my shepherd").

You can buy a used copy of that book for less than $20 at Amazon. Just be sure you order the 1973 version.

Youtube has many versions of this song. The tune I remember best is here. but the words are a bit fuzzy. Is this the tune you're looking for?