The round object looks like it could be a horse bridal rosette. I have found about six up here in vermont. It would be of brass on the outside and filled with lead or iron. It appears to be about the right size.
Is that the tip from a belt or pike axe? I think the spike on those axes was usually straight but it may have gotten bent on a hard skull and broke off. May be part of an old pick axe.
If the third item is a Quater I think the second item is a 3 ring bullet. The bottom right does look like part of a rosette. I just found part of one this past weekend. Not sure about the rest.
Have a Great Day!
Im going detecting at lunch