The glorious old 1917 Oxford Book of English Mystical Verse is in the public domain. It has its wild deficiencies, as does everything else here below, but you’ll find some gems in it and directions for further research and reading.

• a well-proofread electronic text at bartleby.com
• scanned images of yellowed pages at archive.org

Electronic text has its advantages, but for recreational reading on my tablet I prefer to look at letters pressed into yellowed paper.