Females being heirs, or conveying feodal lordships to their husbands, had, as early as the thirteenth century, the privilege of armorial seals.

-From Inquiries into the Origin and Progress of the Science of Heraldry in England by James Dallaway, p443

Seal of Richard, Duke of York

From Inquiries into the Origin and Progress of the Science of Heraldry in England by James Dallaway, p447

3rd Duke of York (1411-1460) c.1430?

Blazon: Per quarterly I and IV azure three fleurs-de-lis or (France), II and III gules three lions passant guardant or, armed and langued azure (England), overall a label of three points, each charged with as many torteaux (York)

Crest: On a cap of state gules lined ermine, a lion statant guardant crowned or

It is not clear whether the other figures on the seal are intended to be supporters or not.

Seal of Richard Neville

From Inquiries into the Origin and Process of the Science of Heraldry in England by James Dallaway, p447

16th Earl of Warwick, (1428-1471), c. 1440

Blazon: Per quarterly; I per quarterly i and iv gules a fess between six cross crosslets or (Beauchamp), ii and iii chequy or and azure, a chevron ermine (Newburgh); II per quarterly i and iv argent three lozenges conjoined in fess gules, ii and iii or an eagle displayed vert armed and langued gules (Montagu); III gules a saltire argent (Neville), a label of three points of the last, on each point two bars azure (Lancaster); IV per quarterly i and iv or three chevronels gules (De Clare), ii and iii per quarterly argent and gules a fret or, overall a bend sable (Despencer)

Supporters: On the dexter a bear rampant, on the sinister a griffin rampant segreant (tinctures unknown)

The dexter crest appears to be some kind of bird rising, possibly an eagle. The sinister looks to be a griffin’s head and wings. Unfortunately, I cannot find any sources to confirm either the crests or the supporters.

Seal of Beatrice Stafford

From Inquiries into the Origin and Process of the Science of Heraldry in England by James Dallaway, p447

c. 1404

Blazon: Tierced per pale; I gules three water-bougets argent (Ros); II or a chevron gules (Stafford); III barry of six sable and or, on a chief of the last two palets of the first, surmounted in the fess point by an escutcheon gules, three bars ermine (Burley)

The figures on either side of the escutcheon appear to be dogs, though I do not believe they are supporters proper, as it would be very rare for a woman to bear supporters in her own right at the time, and I cannot confirm that they belong either to her father or any of her husbands. I believe it is more likely that they were added as decoration.

Dallaway incorrectly identifies this seal as being of Stafford’s third husband, Sir Simon Burley, and perhaps he did possess it after her death, but only the sinistermost coat of arms properly belonged to him.

Nor is it improbable, that, with the inundation of heraldic conceits which prevailed in this kingdom, after the first conquest of France, that of “Les armes parlantes,” or punning arms, was first brought to us, as may be collected from a seal of Sir Peter Le Vele, or De Vitulis, in 1350, who bears calves as his ensign.

-From Inquiries into the Science and Process of the Science of Heraldry in England by James Dallaway, p307-308