The Statement of Randolph Carter
First published in 1920 and then reprinted in the February 1925 and August 1937 issues of Weird Tales, The Statement of Randolph Carter is the first appearance of the titular character and forms of part of H.P. Lovecraft's Dream Cycle.
Due to its length, it might certainly have been the first thing your 11-year-old self read when you first found a book of Lovecraft stories. :)