Answer: Dipylidium caninum proglottid and egg packets
As Micro Michigan pointed out, the proglottid has a nice 'rice grain' appearance and there is also a characteristic egg packet containing round eggs with hooklets.
Luke pointed out that the showing just a single genital pore is a bit confusing since D. caninum has 2 lateral genital pores, thus giving it the name "double-pored" tapeworm. However, Florida Fan clarified that 2 pores were actually present in this case, but that the second one did not capture well by photography.
Here is a photo from one of my very early cases (number 72 - June 2009!) that shows a carmine-stained proglottid with 2 well-defined lateral genial pores (arrows).