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