All of the skulls were picked up while walking or salvaged from roadkill. I would let them weather as much as necessary, clean them up and then soak them in the three-percent hydrogen peroxide available at most grocery or drug stores. I would then glue them together with a crazy glue and spray with a clear lacquer for preservation.
Below, a coyote.
O’Possum. Note the ridge on top.
Deer skull. Probably a White-Tailed deer. Its antlers were sawed off. If it was killed in season and the antlers taken but not the meat, that is illegal. If it was found dead and the antlers taken, another matter entirely. I found it February 2 and the carcass was quite whole. Hunting ended in that area December 15. You do the math.
This animal died after its antlers had dropped naturally, probably after the first of March. This is a weak time for deer.