Yes that is kitty thinking "hey this looks a lot like my litter box"
I originally had the plastic "grass" that goes in Easter baskets but J was not impressed with it and the first thing she always did was pull it all out and throw it to the side.
The original contents of the box included some plastic eggs, felt shapes (eggs, rabbits, chicks), small satin flowers, and small silk flower. I have also now added some feathers I found after I made it that are in Easter colours.
I had one of those I can't believe I didn't foresee that happening moments J is not that interested in keeping the rice OVER the tub which lead to a bigger mess than I anticipated. By bigger mess I mean I had to vacuum the whole living room instead of sweep up a small area. It cost me a whole extra 10 minutes and it was well worth it for how excited she was.
After our first go with it I invested in a vinyl table cloth to use as a drop cloth and now 99% of the mess stays on the drop cloth so I can scoop it back into the tub after J is done and just shake the drop cloth in the trash with the rest.
At the moment J's favorite activities are filling the eggs with rice so they make a nice sound and burying different items so she can dig and find them. Seeing her excitement with the tub has made me excited to think of new ideas for changing it up as the season changes and new holidays approach.