Thankfully, Ray Trygstad, LCDR USN (Retired), a former Navy ROTC Assistant Professor and former Midshipman at the U.S. Naval Academy has identified all of these pins for us. He wrote:
The "(8) Old Gold Filled Navy Anchor Pins" on your page are the following:
Bottom center: U.S. Navy Midshipman cap insignia worn by Naval Academy and Reserve Office Training Corps Midshipmen and by Navy Officer Candidates.
Bottom left and right: U.S. Navy Midshipman left side coat insignia for wear on Service Dress Blue/Full Dress Blue coats. (Both are left-side insignia)
Top row: U.S. Navy Midshipman collar insignia for Third-Class (Sophomore) and Second-Class (Junior) Midshipmen for wear on khaki or blue working uniforms. 2/C wear both anchors with the ends of the ropes pointed out. 3/C wear one anchor on the right collar with the end of the rope pointed out. So you have two pairs of MIDN 2/C anchors and one MIDN 3/C anchor.