Green’s Dictionary of Slang

1. a beggar.

1600		J. Day Blind Beggar of Bednall-Green Act V: How? marry with a Beggar? mix the blood of Strowds with a tatter? either cast her off, or I will cast off thee.
1637		T. Heywood Royal King and Loyal Subject II ii: What tatter’s that that walks there?

2. a rag gatherer.

1882		Dundee Courier (Scot.) 3 Nov. 7/6: In every lage lodging house [...] several trades are almost certain to be found [...] ‘tatter’ (rag gatherer).
1884		‘Career of a Scapegrace’ in Leicester Chron. 10 May 12/1: Paddy was a tatter (a rag buyer) as well as the keeper of a dossing crib.

3. see tat n.¹ (1)