i found an ipad at a yard sale and it is locked can i foctory reset it and use it

Here are the Apple support pages that outline the Activation Lock - and the only mechanisms by which it can be turned off:

https://support.apple.com/en-us/HT201365

https://support.apple.com/en-gb/HT201441

As you will discover, unless you are the owner of the AppleID that was last used to activate the device, or unless you can secure the cooperation of the previous owner, you’ll not be able to defeat or bypass the Activation Lock. Without documentary evidence that you are the original owner (such as sales receipt showing the serial number), Apple won’t assist - and nobody here will be able to help you.

No, you can’t

Turn off Activation Lock - Apple Support

All you can do is recycle it.

Nope. It's a useless device to you. See this link --> The All Too Common SAD Reality of Buying … - Apple Community

Do not purchase untried Apple iOS devices from unknown, untrusted sources which includes thrift stores, pawn shops, auctions and any type of yard/lawn/tag sales.

Recycle this device responsibly.