Child screams if other children tries to play with her toys. Holds as many as she can.
I might actually try it the other way around. Pass her lots of toys if she wants toys. As many as she can hold. Make it a game. Balance one on her head. Make it so there are so many toys floating around that there is room for someone else to use one without her even noticing.
Having doubles of favourites can be a good ploy - not expensive things, just soft toys or cars or whatever ("there's one for you to play with and one for Freddie.")
Suggest that visitors bring toys with them, to act as collateral, or as things for them to play with if she'd prefer not to share hers.
Make sure that her favourite toys are put carefully out of sight when people are visiting - of course she can ask for them if she wants them, but it means the visitors don't even know those toys exist and avoids the conflict.
Make activities for visiting children which don't involve sharing against anyone's will. Bubbles. Paddling pool. Lots of balloons to blow up and bat around. A mattress or cushions to jump on.
Remember - the toys at your house are her toys. You don't lend books unless you feel like lending them. She shouldn't have to lend her toys. I think respecting our children's property is an important starting point, personally.
It will pass, but it is so so so much easier to talk about lending and the concept of X playing with a toy and then they'll give it back and in general the concept of ownership when her language is more developed - around 2.5 or 3 I guess. I'd be finding ways of managing things as they are at her developmental stage just now rather than trying to get sharing to be ok (it's like this magic word isn't it? the adults say "share share share" and the children hear "give away your toys, give away your toys". They just don't understand it as an ok thing at this age. We have to wait for them to be ready)