Here are some with immigrant ancestors with royal and Magna Carta lines on wikitree:

Immigrant Boynton-9 to MC; Clavering-13, Clare-651, Clare-673, Bigod-14, Bigod-1, Lacy-284, Mandeville-10 (nephew), Quincy-226, Marshal-4

Immigrant Bartlett-1867 to Marshal-4, Bohun-7 (nephew), Huntingfield-11 (nephew)

Immigrant Clapp-797 to Clare-651 (nephew), Clavering-13 (nephew), Mowbray-151 (nephew), Mandeville-10 (nephew)

Immigrant Lothrop-3 to Bigod-1, Bigod-14, Bohun-7, Clavering-13, Lanvellei-5, Mowbray-151 (nephew), Fitzwalter-101, Marshal 4

Immigrant Parke-9 to Clare-673, Clare-651, Quincy-226, Marshal-4

Immigrante Porter-152 to Bigod-1, Bigod-14, Clare-673, Clare-661, Clavering-13, Lacy-284, Lanvallei-5, Mowbray-151, Quincy-226, Fitzwalter-101, Marshal-4.

Other immigrant ancestors with royal lines: Scott-217, Carpenter-19, 201, 337, Kimball-138.

I sincerely hope a couple are valid! Let me know if I can help.