can a fellow write a LOR or can it only be an attending? thanks.
Anyone can write a LOR.
I think what you actually want to know is how useful is that LOR.
To which I will say...
There is a hierarchy to the letters, with the higher ones carrying more weight during the application process.
1. Letters from program directors in the specialty you are applying to
2. Letters from faculty of residency programs in the specialty you are applying
3. Letters from faculty at academic institutions in the specialty you want
4. Letters from practitioners of the specialty you are applying to
5. Letters from practitioners in another field but are also faculty of a residency program
6. Letters from practitioners in another field, non academically affiliated
7. Letters from administrators at your school
8. Letters from fellows/residents/interns you worked with
9. Letters from your mom saying how smart you are
Additionally, letters obtained during 4th year are better than those obtained during 3rd year because they can better speak to your expanding knowledge base.
This is by no means a hard and fast rule... But generally speaking... which is all we can do here, that's a fairly standard hierarchy.
This isn't to say you should dissuade your mom from writing a letter...