Sitting in a Tree Birthday invitations Everyone loves to celebrate outside especially in the Spring when the trees are blossoming. Invite to birthdays, picnics or a garden party with the lovely card. Sitting in a Tree - Birthday invitations - Pickett's Press. Online invitation card with green tree, green frame and text field. Sitting in a Tree - Birthday invitations - Pickett's Press. Card with green tree on the side, green frame and text field.