Greetings JoelAppleseed,
Thanks for visiting the Apple Support Communities! It seems you're unable to send photos using Mail Drop on your Mac.
Check out the limits within the following article: Mail Drop limits - Apple Support
"Attachments might not be sent using Mail Drop if they exceed these limits:
- The message, including its attachments, is larger than 5 GB. Try sending the contents of your message in multiple email messages or compressing your attachments to make them as small as possible.
- An uncompressed folder is attached to the message. Use these steps to compress your attachments.
- Too many messages have been sent or the maximum number of recipients has been exceeded. Learn about mailbox size and message sending limits.
- You reached the 1 TB Mail Drop storage limit. Each attachment expires after 30 days, so you can send new attachments after earlier attachments expire and more storage becomes available."
If the issue isn't related to the limits above, test with a different user account to help isolate the behavior: How to test an issue in another user account on your Mac - Apple Support
Kind regards.