What is this tissue?
I'm not really sure, but it seems like a cross section of intestinal villi / intestinal glands from the large intestine.

Here are some images:


Jubal Harshaw. Large intestine villi cross sectioned showing goblet cells_100X_CS0187 on ShutterStock
Jubal Harshaw. Large intestine villi shown in both longitudinal section and cross section on ShutterStock
Garry DeLong. Light micrograph of large intestine villi in cross section, showing goblet cells (Magnification x400) on Getty Images
Hill, M.A. (2014) Embryology Gastrointestinal Tract - Colon Histology. Retrieved September 24, 2014, from https://php.med.unsw.edu.au/embryology/index.php?title=Gastrointestinal_Tract_-_Colon_Histology


And this is one image from the last link:


  Crypts of Lieberkühn - (intestinal gland, intestinal crypt) [...] Transverse